Thin-film magnetic head and method of manufacturing same

ABSTRACT

A thin-film magnetic head comprises a bottom pole layer having a surface that faces toward a write gap layer. This surface incorporates a first surface including an end portion located in the air bearing surface, and a second surface located away from the air bearing surface. There is a difference in level between the first surface and the second surface, so that the second surface is located farther from the top pole layer than the first surface. A top pole layer incorporates a throat height defining layer, an intermediate layer, and a yoke portion layer. The yoke portion layer includes a track width defining portion for defining the track width. Each of the throat height defining layer, the intermediate layer, and the track width defining portion has a width equal to the track width.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a thin-film magnetic head having atleast an induction-type electromagnetic transducer and a method ofmanufacturing such a thin-film magnetic head.

2. Description of the Related Art

Recent years have seen significant improvements in the areal recordingdensity of hard disk drives. In particular, areal recording densities oflatest hard disk drives have reached 100 to 160 gigabytes per platterand are even exceeding that level. It is required to improve theperformance of thin-film magnetic heads, accordingly.

Among the thin-film magnetic heads, widely used are composite thin-filmmagnetic heads made of a layered structure including a recording (write)head having an induction-type electromagnetic transducer for writing anda reproducing (read) head having a magnetoresistive element (that may behereinafter called an MR element) for reading.

In general, the write head incorporates: a medium facing surface (an airbearing surface) that faces toward a recording medium; a bottom polelayer and a top pole layer that are magnetically coupled to each otherand include magnetic pole portions opposed to each other and located inregions of the pole layers on a side of the medium facing surface; awrite gap layer provided between the magnetic pole portions of the topand bottom pole layers; and a thin-film coil at least part of which isdisposed between the top and bottom pole layers and insulated from thetop and bottom pole layers.

Higher track densities on a recording medium are essential to enhancingthe recording density among the performances of the write head. Toachieve this, it is required to implement the write head of a narrowtrack structure in which the track width, that is, the width of the twomagnetic pole portions opposed to each other with the write gap layerdisposed in between, the width being taken in the medium facing surface,is reduced down to microns or the order of submicron. Semiconductorprocess techniques are utilized to achieve the write head having such astructure. In addition, many write heads have a trim structure toprevent an increase in the effective track width due to expansion of amagnetic flux generated in the pole portions in the medium facingsurface. The trim structure is a configuration in which the pole portionof the top pole layer, the write gap layer and a portion of the bottompole layer have the same width taken in the medium facing surface. Thisstructure is formed by etching the write gap layer and the portion ofthe bottom pole layer, using the pole portion of the top pole layer as amask.

One of the performance characteristics required for the write head is anexcellent overwrite property that is one of the characteristics requiredfor overwrite. To improve the overwrite property, it is required that asmany magnetic lines of flux passing through the two pole layers aspossible be introduced to the pole portions so as to generate a magneticfield as large as possible near the write gap layer in the medium facingsurface. Therefore, to improve the overwrite property, it is effectiveto employ a material having a high saturation flux density for themagnetic material of the pole portions, and to reduce the throat height.The throat height is the length (height) of the pole portions, that is,the portions of the two pole layers opposed to each other with the writegap layer in between, as taken from the medium-facing-surface-side endto the other end. The zero throat height level is the level of the end(opposite to the medium facing surface) of the portions of the two polelayers opposed to each other with the write gap layer in between. Toimprove the overwrite property, it is also effective to increase thedistance between the two pole layers in a region farther from the mediumfacing surface than the zero throat height level.

However, a problem arises if many lines of flux are introduced to thepole portions to improve the overwrite property. The problem is thatlines of flux leak from portions in the medium facing surface other thanthe neighborhood of the write gap layer, and the flux leakage causesside write and side erase. Side write is that data is written in a trackadjacent to the intended track. Side erase is that data written in atrack adjacent to the intended track is erased. To reduce theoccurrences of side write and side erase, it is effective to increasethe difference in levels of the bottom pole layer in the trim structure,that is, the difference between the level of a portion of an end face ofthe bottom pole layer exposed in the medium facing surface, the portiontouching the write gap layer, and the level of portions on both sides.

The throat height may be determined by forming a stepped portion in thebottom or top pole layer. Methods of determining the throat height byforming a stepped portion in the bottom pole layer are disclosed in, forexample, the U.S. Pat. No. 6,259,583B1, the U.S. Pat. No. 6,400,525B1,and the U.S. Pat. No. 5,793,578. Methods of determining the throatheight by forming a stepped portion in the top pole layer are disclosedin, for example, the U.S. Pat. No. 6,043,959 and the U.S. Pat. No.6,560,068B1.

The following problem arises if the throat height is determined byforming a stepped portion in the bottom pole layer. To improve theoverwrite property, it is effective to reduce the throat height and toincrease the difference in levels in the bottom pole layer thatdetermines the throat height. To reduce the occurrences of side writeand side erase, it is effective to increase the difference in levels ofthe bottom pole layer in the trim structure. To achieve this, however,the volume of the portion of the bottom pole layer located between theside portions forming the trim structure is extremely reduced. At thesame time, the cross-sectional area of the magnetic path abruptlydecreases in the neighborhood of the boundary between theabove-mentioned portion of the bottom pole layer and the other portions.As a result, the flux saturates in the neighborhood of the boundary andthe overwrite property is reduced. Furthermore, the end face of thebottom pole layer exposed in the medium facing surface has a width thatabruptly changes at the bottom of the stepped portion of the trimstructure. Consequently, the flux leaks from the neighborhood of thebottom of the stepped portion of the trim structure toward the recordingmedium, which causes side write and side erase.

In the case in which the throat height is determined by forming astepped portion in the top pole layer, too, a problem is that theoverwrite property is reduced if the cross-sectional area of themagnetic path of the top pole layer abruptly decreases in theneighborhood of the medium facing surface.

The following problem also arises if the throat height is determined byforming a stepped portion in the top pole layer. In prior art thestepped portion of the top pole layer that determines the throat heightis formed as follows. A pole portion layer that determines the throatheight is first formed on the write gap layer. Next, an insulating layeris formed to cover the pole portion layer and the write gap layer. Theinsulating layer is polished so that the top surface of the pole portionlayer is exposed. According to this method, the thickness of the poleportion layer varies, depending on the depth removed by theabove-mentioned polishing. It is therefore difficult to preciselycontrol the writing characteristics of the head if this method isemployed.

OBJECT AND SUMMARY OF THE INVENTION

It is an object of the invention to provide a thin-film magnetic headand a method of manufacturing the same to reduce the occurrences of sidewrite and side erase and to improve the overwrire property of thethin-film magnetic head.

A thin-film magnetic head of the invention comprises: a medium facingsurface that faces toward a recording medium; a first pole layer and asecond pole layer that are magnetically coupled to each other andinclude magnetic pole portions opposed to each other and located inregions of the pole layers on a side of the medium facing surface; a gaplayer provided between the pole portion of the first pole layer and thepole portion of the second pole layer; and a thin-film coil, at leastpart of the coil being disposed between the first and second pole layersand insulated from the first and second pole layers. The first polelayer has a surface facing toward the gap layer, the surfaceincorporating a first surface including an end portion located in themedium facing surface and an end portion located opposite to the mediumfacing surface, and a second surface located away from the medium facingsurface. The first surface is adjacent to the gap layer. A difference inlevel is created between the first surface and the second surface, sothat the second surface is located farther from the second pole layerthan the first surface. The second pole layer incorporates: a firstlayer disposed adjacent to the gap layer and including an end portionlocated in the medium facing surface and an end portion located oppositeto the medium facing surface; and a second layer disposed on a side ofthe first layer opposite to the gap layer and including a track widthdefining portion for defining a track width. Each of the first layer andthe second layer has a width taken in the medium facing surface that isequal to the track width. The length of the second layer is greater thanthe length of the first layer, each of the lengths being taken in adirection orthogonal to the medium facing surface.

According to the thin-film magnetic head of the invention, the firstpole layer may include a portion adjacent to the gap layer, the portionhaving a width taken in the medium facing surface that is equal to thetrack width. The second layer may be a flat layer.

The thin-film magnetic head of the invention may further comprise anintermediate layer disposed between the first layer and the secondlayer. In this case, it is possible that the intermediate layer has awidth taken in the medium facing surface that is equal to the trackwidth, and the length of the intermediate layer taken in the directionorthogonal to the medium facing surface is greater than the length ofthe first layer and smaller than the length of the second layer. In thiscase, the throat height may be defined by the end portion of the firstlayer opposite to the medium facing surface.

According to the thin-film magnetic head of the invention, the throatheight may be defined by the position in which the first layer is incontact with an end portion of the gap layer opposite to the mediumfacing surface.

According to the thin-film magnetic head of the invention, it ispossible that the throat height is defined by the end portion of thefirst layer opposite to the medium facing surface and that the endportion of the first surface of the first pole layer opposite to themedium facing surface is located farther from the medium facing surfacethan the end portion of the first layer opposite to the medium facingsurface.

A method of the invention for manufacturing a thin-film magnetic head isa method of manufacturing the thin-film magnetic head of the invention.The method comprises the steps of: forming the first pole layer; formingthe thin-film coil on the first pole layer; forming the gap layer on thepole portion of the first pole layer; and forming the second pole layeron the gap layer.

The step of forming the second pole layer includes the steps of: forminga magnetic layer for forming the first layer on the gap layer; formingthe second layer on the magnetic layer; and etching the magnetic layerto align with the width of the track width defining portion, so that themagnetic layer is formed into the first layer and that the width of eachof the first layer and the second layer taken in the medium facingsurface is made equal to the track width.

According to the method of manufacturing the thin-film magnetic head ofthe invention, the step of etching the magnetic layer may furtherinclude etching of the gap layer and a portion of the first pole layerto align with the width of the track width defining portion.

According to the method of the invention, the second layer may be madeto be a flat layer.

According to the method of the invention, it is possible that the gaplayer is made of a nonmagnetic inorganic material and that the firstlayer is etched by reactive ion etching in the step of etching the firstlayer. In this case, the nonmagnetic inorganic material may be one ofthe group consisting of alumina, silicon carbide and aluminum nitride.

According to the method of the invention, the second pole layer mayfurther comprise an intermediate layer disposed between the first layerand the second layer. In this case, the intermediate layer may have awidth taken in the medium facing surface that is equal to the trackwidth, and may have a length taken in the direction orthogonal to themedium facing surface that is greater than the length of the first layerand smaller than the length of the second layer.

According to the method of the invention, the step of forming the secondpole layer may include the steps of: forming a first magnetic layer forforming the first layer on the gap layer; forming a first mask on thefirst magnetic layer for forming an end portion of the first magneticlayer opposite to the medium facing surface; forming the end portion ofthe first magnetic layer and forming the first surface and the secondsurface of the first pole layer by selectively etching the firstmagnetic layer, the gap layer and the first pole layer through the useof the first mask; forming a first nonmagnetic layer so as to filletched portions of the first magnetic layer, the gap layer and the firstpole layer while the first mask is left unremoved; removing the firstmask after the first nonmagnetic layer is formed; forming a secondmagnetic layer for forming the intermediate layer on the first magneticlayer and the first nonmagnetic layer after the first mask is removed;forming a second mask on the second magnetic layer for forming an endportion of the second magnetic layer opposite to the medium facingsurface; forming the end portion of the second magnetic layer byselectively etching the second magnetic layer through the use of thesecond mask; forming a second nonmagnetic layer so as to fill an etchedportion of the second magnetic layer while the second mask is leftunremoved; removing the second mask after the second nonmagnetic layeris formed; forming the second layer on the second magnetic layer and thesecond nonmagnetic layer after the second mask is removed; and etchingthe second magnetic layer and the first magnetic layer to align with thewidth of the track width defining portion, so that the first magneticlayer is formed into the first layer, the second magnetic layer isformed into the intermediate layer, and the width of each of the firstlayer, the intermediate layer and the second layer that is taken in themedium facing surface is made equal to the track width.

In this case, the throat height may be defined by the end portion of thefirst layer opposite to the medium facing surface.

The step of forming the second pole layer may further include the stepof flattening the top surfaces of the first magnetic layer and the firstnonmagnetic layer by polishing, the step of flattening being providedbetween the step of removing the first mask and the step of forming thesecond magnetic layer. The depth to which the polishing is performed inthe step of flattening the top surfaces of the first magnetic layer andthe first nonmagnetic layer may fall within a range of 10 to 50 nminclusive. The step of forming the second pole layer may further includethe step of flattening the top surfaces of the second magnetic layer andthe second nonmagnetic layer by polishing, the step of flattening beingprovided between the step of removing the second mask and the step offorming the second layer. The depth to which the polishing is performedin the step of flattening the top surfaces of the second magnetic layerand the second nonmagnetic layer may fall within a range of 10 to 50 nminclusive.

According to the method of the invention, the step of forming the firstpole layer may include the steps of: forming a first mask for formingthe first surface and the second surface of the first pole layer on thegap layer; forming the first surface and the second surface byselectively etching the gap layer and a portion of the first pole layerthrough the use of the first mask; forming a first nonmagnetic layer soas to fill etched portions of the gap layer and the first pole layerwhile the first mask is left unremoved; and removing the first maskafter the first nonmagnetic layer is formed.

In addition, the step of forming the second pole layer may include thesteps of: forming a magnetic layer for forming the first layer on thegap layer and the first nonmagnetic layer after the first mask isremoved; forming a second mask on the magnetic layer for forming an endportion of the magnetic layer opposite to the medium facing surface;forming the end portion of the magnetic layer by selectively etching themagnetic layer through the use of the second mask; forming a secondnonmagnetic layer so as to fill an etched portion of the magnetic layerwhile the second mask is left unremoved; removing the second mask afterthe second nonmagnetic layer is formed; forming the second layer on themagnetic layer and the second nonmagnetic layer after the second mask isremoved; and etching the magnetic layer to align with the width of thetrack width defining portion, so that the magnetic layer is formed intothe first layer and that the width of each of the first layer and thesecond layer that is taken in the medium facing surface is made equal tothe track width.

In this case, it is possible that an end portion of the gap layeropposite to the medium facing surface is formed by the etching of thegap layer and that the throat height is defined by a position in whichthe end portion of the gap layer is in contact with the first magneticlayer.

The step of forming the second pole layer may further include the stepof flattening the top surface of the magnetic layer by polishing beforethe second mask is formed on the magnetic layer. The depth to which thepolishing is performed in the step of flattening the top surface of themagnetic layer may fall within a range of 10 to 50 nm inclusive. Thestep of forming the second pole layer may further include the step offlattening the top surfaces of the magnetic layer and the secondnonmagnetic layer by polishing, the step of flattening being providedbetween the step of removing the second mask and the step of forming thesecond layer. The depth to which the polishing is performed in the stepof flattening the top surfaces of the magnetic layer and the secondnonmagnetic layer may fall within a range of 10 to 50 nm inclusive.

According to the method of the invention, the step of forming the firstpole layer may include the steps of: forming a first mask for formingthe first surface and the second surface of the first pole layer on thefirst pole layer; forming the first surface and the second surface byselectively etching a portion of the first pole layer through the use ofthe first mask; forming a first nonmagnetic layer so as to fill anetched portion of the first pole layer while the first mask is leftunremoved; and removing the first mask after the first nonmagnetic layeris formed. The step of forming the second pole layer may include thesteps of: forming a magnetic layer for forming the first layer on thegap layer; forming a second mask on the magnetic layer for forming anend portion of the magnetic layer opposite to the medium facing surface;forming the end portion of the magnetic layer by selectively etching themagnetic layer through the use of the second mask; forming a secondnonmagnetic layer so as to fill an etched portion of the magnetic layerwhile the second mask is left unremoved; removing the second mask afterthe second nonmagnetic layer is formed; forming the second layer on themagnetic layer and the second nonmagnetic layer after the second mask isremoved; and etching the magnetic layer to align with the width of thetrack width defining portion, so that the magnetic layer is formed intothe first layer and that the width of each of the first layer and thesecond layer that is taken in the medium facing surface is made equal tothe track width.

In this case, it is possible that the throat height is defined by theend portion of the first layer opposite to the medium facing surface andthat the end portion of the first surface of the first pole layeropposite to the medium facing surface is located farther from the mediumfacing surface than the end portion of the first layer opposite to themedium facing surface.

The step of forming the first pole layer may further include the step offlattening the top surfaces of the first pole layer and the firstnonmagnetic layer by polishing after the first mask is removed. Thedepth to which the polishing is performed in the step of flattening thetop surfaces of the first pole layer and the first nonmagnetic layer mayfall within a range of 10 to 50 nm inclusive. The step of forming thesecond pole layer may further include the step of flattening the topsurfaces of the magnetic layer and the second nonmagnetic layer bypolishing, the step of flattening being provided between the step ofremoving the second mask and the step of forming the second layer. Thedepth to which the polishing is performed in the step of flattening thetop surfaces of the magnetic layer and the second nonmagnetic layer mayfall within a range of 10 to 50 nm inclusive.

According to the invention, the cross-sectional area of each of themagnetic path of the first pole layer and the magnetic path of thesecond pole layer gradually changes in the neighborhood of the mediumfacing surface. Therefore, according to the invention, the overwriteproperty of the thin-film magnetic head is improved while theoccurrences of side write and side erase are suppressed.

Other and further objects, features and advantages of the invention willappear more fury from the following description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A and FIG. 1B are cross-sectional views for illustrating a step ina method of manufacturing a thin-film magnetic head of a firstembodiment of the invention.

FIG. 2A and FIG. 2B are cross-sectional views for illustrating a stepthat follows FIG. 1A and FIG. 1B.

FIG. 3A and FIG. 3B are cross-sectional views for illustrating a stepthat follows FIG. 2A and FIG. 2B.

FIG. 4A and FIG. 4B are cross-sectional views for illustrating a stepthat follows FIG. 3A and FIG. 3B.

FIG. 5A and FIG. 5B are cross-sectional views for illustrating a stepthat follows FIG. 4A and FIG. 4B.

FIG. 6A and FIG. 6B are cross-sectional views for illustrating a stepthat follows FIG. 5A and FIG. 5B.

FIG. 7A and FIG. 7B are cross-sectional views for illustrating a stepthat follows FIG. 6A and FIG. 6B.

FIG. 8A and FIG. 8B are cross-sectional views for illustrating a stepthat follows FIG. 7A and FIG. 7B.

FIG. 9A and FIG. 9B are cross-sectional views for illustrating a stepthat follows FIG. 8A and FIG. 8B.

FIG. 10A and FIG. 10B are cross-sectional views for illustrating a stepthat follows FIG. 9A and FIG. 9B.

FIG. 11A and FIG. 11B are cross-sectional views for illustrating a stepthat follows FIG. 10A and FIG. 10B.

FIG. 12A and FIG. 12B are cross-sectional views for illustrating a stepthat follows FIG. 11A and FIG. 11B.

FIG. 13A and FIG. 13B are cross-sectional views for illustrating a stepthat follows FIG. 12A and FIG. 12B.

FIG. 14A and FIG. 14B are cross-sectional views for illustrating a stepthat follows FIG. 13A and FIG. 13B.

FIG. 15A and FIG. 15B are cross-sectional views for illustrating a stepthat follows FIG. 14A and FIG. 14B.

FIG. 16A and FIG. 16B are cross-sectional views for illustrating a stepthat follows FIG. 15A and FIG. 15B.

FIG. 17A and FIG. 17B are cross-sectional views for illustrating a stepthat follows FIG. 16A and FIG. 16B.

FIG. 18 is a plan view for illustrating the shape and arrangement of thethin-film coil of the thin-film magnetic head of the first embodiment ofthe invention.

FIG. 19 is a perspective view for illustrating the configuration of thethin-film magnetic head of the first embodiment.

FIG. 20A and FIG. 20B are cross-sectional views for illustrating a stepin a modification example of the method of manufacturing the thin-filmmagnetic head of the first embodiment.

FIG. 21A and FIG. 21B are cross-sectional views for illustrating a stepin a method of manufacturing a thin-film magnetic head of a secondembodiment of the invention.

FIG. 22A and FIG. 22B are cross-sectional views for illustrating a stepthat follows FIG. 21A and FIG. 21B.

FIG. 23A and FIG. 23B are cross-sectional views for illustrating a stepthat follows FIG. 22A and FIG. 22B.

FIG. 24A and FIG. 24B are cross-sectional views for illustrating a stepthat follows FIG. 23A and FIG. 23B.

FIG. 25A and FIG. 25B are cross-sectional views for illustrating a stepthat follows FIG. 24A and FIG. 24B.

FIG. 26A and FIG. 26B are cross-sectional views for illustrating a stepthat follows FIG. 25A and FIG. 25B.

FIG. 27A and FIG. 27B are cross-sectional views for illustrating a stepthat follows FIG. 26A and FIG. 26B.

FIG. 28A and FIG. 28B are cross-sectional views for illustrating a stepin a method of manufacturing a thin-film magnetic head of a thirdembodiment of the invention.

FIG. 29A and FIG. 29B are cross-sectional views for illustrating a stepthat follows FIG. 28A and FIG. 28B.

FIG. 30A and FIG. 30B are cross-sectional views for illustrating a stepthat follows FIG. 29A and FIG. 29B.

FIG. 31A and FIG. 31B are cross-sectional views for illustrating a stepthat follows FIG. 30A and FIG. 30B.

FIG. 32A and FIG. 32B are cross-sectional views for illustrating a stepthat follows FIG. 31A and FIG. 31B.

FIG. 33A and FIG. 33B are cross-sectional views for illustrating a stepthat follows FIG. 32A and FIG. 32B.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of the invention will now be described in detail withreference to the accompanying drawings.

First Embodiment

Reference is now made to FIG. 1A to FIG. 17A, FIG. 1B to FIG. 17B, FIG.18 and FIG. 19 to describe a method of manufacturing a thin-filmmagnetic head of a first embodiment of the invention. FIG. 1A to FIG.17A are cross sections orthogonal to the air bearing surface and the topsurface of a substrate. FIG. 1B to FIG. 17B are cross sections ofmagnetic pole portions each of which is parallel to the air bearingsurface. FIG. 18 is a plan view showing the shape and arrangement of athin-film coil of the thin-film magnetic head of the embodiment. FIG. 19is a perspective view for illustrating the configuration of thethin-film magnetic head in which an overcoat layer is omitted.

In the method of manufacturing the thin-film magnetic head of theembodiment, a step shown in FIG. 1A and FIG. 1B is first performed. Inthe step an insulating layer 2 made of alumina (Al₂O₃), for example, isdeposited to a thickness of approximately 1 to 3 μm on a substrate 1made of aluminum oxide and titanium carbide (Al₂O₃—TiC), for example.Next, a bottom shield layer 3 for a read head, made of a magneticmaterial such as Permalloy and having a thickness of approximately 2 to3 μm, is formed on the insulating layer 2. The bottom shield layer 3 isselectively formed on the insulating layer 2 by plating through the useof a photoresist film as a mask, for example. Although not shown, aninsulating layer that is made of alumina, for example, and has athickness of 3 to 4 μm, for example, is formed over the entire surface.The insulating layer is then polished by chemical mechanical polishing(hereinafter referred to as CMP), for example, to expose the bottomshield layer 3 and to flatten the surface.

On the bottom shield layer 3, a bottom shield gap film 4 serving as aninsulating film and having a thickness of approximately 20 to 40 nm, forexample, is formed. On the bottom shield gap film 4, an MR element 5 formagnetic signal detection having a thickness of tens of nanometers isformed. For example, the MR element 5 may be formed by selectivelyetching an MR film formed by sputtering. The MR element 5 is locatednear a region in which the air bearing surface described later is to beformed. The MR element 5 may be an element made up of a magnetosensitivefilm that exhibits magnetoresistivity, such as an AMR element, a GMRelement or a TMR (tunnel magnetoresistive) element. Next, although notshown, a pair of electrode layers, each having a thickness of tens ofnanometers, to be electrically connected to the MR element 5 are formedon the bottom shield gap film 4. A top shield gap film 7 serving as aninsulating film and having a thickness of approximately 20 to 40 nm, forexample, is formed on the bottom shield gap film 4 and the MR element 5.The MR element 5 is embedded in the shield gap films 4 and 7. Examplesof insulating materials used for the shield gap films 4 and 7 includealumina, aluminum nitride, and diamond-like carbon (DLC). The shield gapfilms 4 and 7 may be formed by sputtering or chemical vapor deposition(hereinafter referred to as CVD).

Next, a top shield layer 8 for a read head, made of a magnetic materialand having a thickness of approximately 1.0 to 1.5 μm, is selectivelyformed on the top shield gap film 7. Next, although not shown, aninsulating layer made of alumina, for example, and having a thickness of2 to 3 μm, for example, is formed over the entire surface, and polishedby CMP, for example, so that the top shield layer 8 is exposed, and thesurface is flattened.

An insulating layer 9 made of alumina, for example, and having athickness of approximately 0.3 μm, for example, is formed over theentire top surface of the layered structure obtained through theforegoing steps. On the entire top surface of the insulating layer 9, afirst layer 10 a of the bottom pole layer 10 made of a magnetic materialand having a thickness of approximately 0.5 to 1.0 μm is formed. Thefirst layer 10 a has a top surface that is flat throughout. The bottompole layer 10 includes the first layer 10 a, and a second layer 10 b, athird layer 10 d, a fourth layer 10 f, and coupling layers 10 c, 10 eand 10 g that will be described later.

The first layer 10 a may be formed by plating, using NiFe (80 weight %Ni and 20 weight % Fe), or a high saturation flux density material suchas NiFe (45 weight % Ni and 55 weight % Fe), CoNiFe (10 weight % Co, 20weight % Ni and 70 weight % Fe), or FeCo (67 weight % Fe and 33 weight %Co). Alternatively, the first layer 10 a may be formed by sputtering,using a high saturation flux density material such as CoFeN, FeAlN, FeN,FeCo, or FeZrN. In this embodiment the first layer 10 a is formed bysputtering to have a thickness of 0.5 to 1.0 μm by way of example.

Next, an insulating film 11 made of alumina, for example, and having athickness of 0.2 μm, for example, is formed on the first layer 10 a. Theinsulating film 11 is then selectively etched to form openings in theinsulating film 11 in regions in which the second layer 10 b and thecoupling layer 10 c are to be formed.

Next, although not shown, an electrode film of a conductive materialhaving a thickness of 50 to 80 nm is formed by sputtering, for example,so as to cover the first layer 10 a and the insulating film 11. Thiselectrode film functions as an electrode and a seed layer for plating.Next, although not shown, a frame is formed on the electrode film byphotolithography. The frame will be used for forming a first coil 13 byplating.

Next, electroplating is performed, using the electrode film, to form thefirst coil 13 made of a metal such as copper (Cu) and having a thicknessof approximately 3.0 to 3.5 μm. The first coil 13 is disposed in theregion in which the insulating film 11 is located. Next, the frame isremoved, and portions of the electrode film except the portion below thefirst coil 13 are then removed by ion beam etching, for example.

Next, although not shown, a frame is formed on the first layer 10 a andthe insulating film 11 by photolithography. The frame will be used forforming the second layer 10 b and the coupling layer 10 c of the bottompole layer 10 by frame plating.

FIG. 2A and FIG. 2B illustrate the following step. In the stepelectroplating is performed to form the second layer 10 b and thecoupling layer 10 c, each of which is made of a magnetic material andhas a thickness of 3.5 to 4.0 μm, for example, on the first layer 10 a.For example, the second layer 10 b and the coupling layer 10 c may bemade of NiFe, CoNiFe or FeCo. In the present embodiment the second layer10 b and the coupling layer 10 c are made of CoNiFe having a saturationflux density of 1.9 to 2.3 tesla (T) by way of example. In theembodiment, when the second layer 10 b and the coupling layer 10 c areformed by plating, no specific electrode film is provided, but theunpatterned first layer 10 a is used as an electrode and a seed layerfor plating.

Next, although not shown, a photoresist layer is formed to cover thefirst coil 13, the second layer 10 b and the coupling layer 10 c. Usingthe photoresist layer as a mask, the first layer 10 a is selectivelyetched by reactive ion etching or ion beam etching, for example. Thefirst layer 10 a is thus patterned. Next, the photoresist layer isremoved.

FIG. 3A and FIG. 3B illustrate the following step. In the step aninsulating layer 15 made of photoresist, for example, is formed in aregion in which a second coil 19 described later is to be located. Theinsulating layer 15 is formed so that at least the space between thesecond layer 10 b and the first coil 13, the space between the turns ofthe first coil 13, and the space between the coupling layer 10 c and thefirst coil 13 are filled with the insulating layer 15. Next, aninsulating layer 16 made of alumina, for example, and having a thicknessof 4 to 6 μm is formed so as to cover the insulating layer 15.

FIG. 4A and FIG. 4B illustrate the following step. In the step theinsulating layers 15 and 16 are polished by CMP, for example, so thatthe second layer 10 b, the coupling layer 10 c and the insulating layer15 are exposed, and the top surfaces of the second layer 10 b, thecoupling layer 10 c and the insulating layers 15 and 16 (which is notshown in FIG. 4A and FIG. 4B) are flattened.

FIG. 5A and FIG. 5B illustrate the following step. In the step theinsulating layer 15 is removed, and an insulating film 17 made ofalumina, for example, is then formed by CVD, for example, so as to coverthe entire top surface of the layered structure. As a result, groovescovered with the insulating film 17 are formed in the space between thesecond layer 10 b and the first coil 13, the space between the turns ofthe first coil 13, and the space between the coupling layer 10 c and thefirst coil 13. The insulating film 17 has a thickness of 0.08 to 0.15μm, for example. The insulating film 17 may be formed by CVD, forexample, wherein a gas of H₂O, N₂O, H₂O₂ or O₃ (ozone) as a materialused for making thin films and Al(CH₃)₃ or AlCl₃ as a material used formaking thin films are alternately ejected in an intermittent mannerunder a reduced pressure at a temperature of 180 to 220° C. Through thismethod, a plurality of thin alumina films are stacked so that theinsulating film 17 that is closely-packed and exhibits a good stepcoverage, and has a desired thickness is formed.

Next, a first conductive film made of Cu, for example, and having athickness of 50 nm, for example, is formed by sputtering so as to coverthe entire top surface of the layered structure. On the first conductivefilm, a second conductive film made of Cu, for example, and having athickness of 50 nm, for example, is formed by CVD. The second conductivefilm is not intended to be used for entirely filling the groove betweenthe second layer 10 b and the first coil 13, the groove between theturns of the first coil 13, and the groove between the coupling layer 10c and the first coil 13, but is intended to cover the grooves, takingadvantage of good step coverage of CVD. The first and second conductivefilms in combination are called an electrode film. The electrode filmfunctions as an electrode and a seed layer for plating. Next, on theelectrode film, a conductive layer 19 p made of a metal such as Cu andhaving a thickness of 3 to 4 μm, for example, is formed by plating. Theelectrode film and the conductive layer 19 p are used for making thesecond coil 19. The conductive layer 19 p of Cu is formed throughplating on the second conductive film of Cu formed by CVD, so that thesecond coil 19 is properly formed in the space between the second layer10 b and the first coil 13, the space between the turns of the firstcoil 13, and the space between the coupling layer 10 c and the firstcoil 13.

FIG. 6A and FIG. 6B illustrate the following step. In the step theconductive layer 19 p is polished by CMP, for example, so that thesecond layer 10 b, the coupling layer 10 c, and the first coil 13 areexposed. As a result, the second coil 19 is made up of the conductivelayer 19 p and the electrode film that remain in the space between thesecond layer 10 b and the first coil 13, the space between the turns ofthe first coil 13, and the space between the coupling layer 10 c and thefirst coil 13. The above-mentioned polishing is performed such that eachof the second layer 10 b, the coupling layer 10 c, the first coil 13 andthe second coil 19 has a thickness of 2.0 to 3.0 μm, for example. Thesecond coil 19 has turns at least part of which is disposed betweenturns of the first coil 13. The second coil 19 is formed such that onlythe insulating film 17 is provided between the turns of the first coil13 and the turns of the second coil 19.

FIG. 18 illustrates the first coil 13 and the second coil 19. FIG. 6A isa cross section taken along line 6A-6A of FIG. 18. Connecting layers 21,46 and 47, the top pole layer 30 and the air bearing surface 42 thatwill be formed later are shown in FIG. 18, too. As shown in FIG. 18, aconnecting portion 13 a is provided near an inner end of the first coil13. A connecting portion 13 b is provided near an outer end of the firstcoil 13. A connecting portion 19 a is provided near an inner end of thesecond coil 19. A connecting portion 19 b is provided near an outer endof the second coil 19.

In the step of forming the first coil 13 or the step of forming thesecond coil 19, two lead layers 44 and 45 are formed to be disposedoutside the first layer 10 a of the bottom pole layer 10, as shown inFIG. 18. The lead layers 44 and 45 have connecting portions 44 a and 45a, respectively.

The connecting portions 13 a and 19 b are connected to each otherthrough a connecting layer 21 that will be formed later. The connectingportions 44 a and 13 b are connected to each other through a connectinglayer 46 that will be formed later. The connecting portions 19 a and 45a are connected to each other through a connecting layer 47 that will beformed later.

FIG. 7A and FIG. 7B illustrate the following step. In the step aninsulating film 20 made of alumina, for example, and having a thicknessof 0.1 to 0.3 μm is formed to cover the entire top surface of thelayered structure. Etching is selectively performed on the insulatingfilm 20 in the portions corresponding to the second layer 10 b, thecoupling layer 10 c, the two connecting portions 13 a and 13 b of thefirst coil 13, the two connecting portions 19 a and 19 b of the secondcoil 19, the connecting portion 44 a of the lead layer 44, and theconnecting portion 45 a of the lead layer 45. The insulating film 20thus etched covers the top surfaces of the coils 13 and 19 except thetwo connecting portions 13 a and 13 b of the first coil 13 and the twoconnecting portions 19 a and 19 b of the second coil 19.

Next, the connecting layers 21, 46 and 47 of FIG. 18 are formed by frameplating, for example. The connecting layers 21, 46 and 47 are made of ametal such as Cu and each have a thickness of 0.8 to 1.5 μm, forexample.

Next, a third layer 10 d is formed on the second layer 10 b, and acoupling layer 10 e is formed on the coupling layer 10 c each by frameplating, for example. The third layer 10 d and the coupling layer 10 emay be made of NiFe, CoNiFe or FeCo, for example. In the embodiment thethird layer 10 d and the coupling layer 10 e are made of CoNiFe having asaturation flux density of 1.9 to 2.3 T by way of example. The thirdlayer 10 d and the coupling layer 10 e each have a thickness of 0.8 to1.5 μm, for example.

Next, an insulating film 22 made of alumina, for example, and having athickness of 1 to 2 μm is formed to cover the entire top surface of thelayered structure. The insulating film 22 is then polished by CMP, forexample. This polishing is performed such that the top surfaces of thethird layer 10 d, the coupling layer 10 e, the connecting layers 21, 46and 47, and the insulating film 22 are flattened and each of theselayers has a thickness of 0.3 to 1.0 μm.

Next, although not shown, a magnetic layer made of a magnetic materialand having a thickness of 0.3 to 0.5 μm is formed by sputtering, so asto cover the entire top surface of the layered structure. The magneticlayer may be made of a high saturation flux density material such asCoFeN, FeAlN, FeN, FeCo, or FeZrN. In the embodiment the magnetic layeris made of CoFeN having a saturation flux density of 2.4 T by way ofexample.

FIG. 8A and FIG. 8B illustrate the following step. In the step, on themagnetic layer, an etching mask 24 a is formed in the portioncorresponding to the third layer 10 d, and an etching mask 24 b isformed in the portion corresponding to the coupling layer 10 e. Each ofthe etching masks 24 a and 24 b has an undercut so that the bottomsurface is smaller than the top surface in order to facilitate lift-offthat will be performed later. Such etching masks 24 a and 24 b may beformed by patterning a resist layer made up of two stacked organicfilms, for example.

Next, the magnetic layer is selectively etched by ion beam etching, forexample, through the use of the etching masks 24 a and 24 b. The fourthlayer 10 f and the coupling layer 10 g are thereby formed on the thirdlayer 10 d and the coupling layer 10 e, respectively. The fourth layer10 f and the coupling layer 10 g are made up of portions of the magneticlayer remaining under the etching masks 24 a and 24 b after the etching.This etching is performed such that the direction in which ion beamsmove forms an angle in a range of 0 to 20 degrees inclusive with respectto the direction orthogonal to the top surface of the first layer 10 a.Next, to remove deposits on the sidewalls of the magnetic layer 23 afterthe etching, another etching is performed such that the direction inwhich ion beams move forms an angle in a range of 60 to 75 degreesinclusive with respect to the direction orthogonal to the top surface ofthe first layer 10 a.

Next, an insulating layer 25 made of alumina, for example, and having athickness of 0.4 to 0.6 μm is formed so as to cover the entire topsurface of the layered structure while the etching masks 24 a and 24 bare left unremoved. The insulating layer 25 is formed in a self-alignedmanner so as to fill the etched portion of the above-mentioned magneticlayer. The etching masks 24 a and 24 b are then lifted off. Next, CMP isperformed for a short period of time, for example, to polish and flattenthe top surfaces of the fourth layer 10 f, the coupling layer 10 g andthe insulating layer 25. This flattening removes small differences inlevels between the fourth layer 10 f and the insulating layer 25, andbetween the coupling layer 10 g and the insulating layer 25, and removesremainders and burrs of the etching masks 24 a and 24 b after lift-offis performed.

FIG. 9A and FIG. 9B illustrate the following step. In the step a writegap layer 26 having a thickness of 0.07 to 0.1 μm is formed to cover theentire top surface of the layered structure. The write gap layer 26 maybe made of an insulating material such as alumina or a nonmagnetic metalmaterial such as Ru, NiCu, Ta, W or NiB. Next, a portion of the writegap layer 26 corresponding to the coupling layer 10 g is selectivelyetched.

Next, a first magnetic layer 27 made of a magnetic material and having athickness of 0.1 to 0.3 μm is formed by sputtering, for example, so asto cover the entire top surface of the layered structure. The magneticlayer 27 may be made of a high saturation flux density material such asCoFeN, FeAlN, FeN, FeCo or FeZrN. The magnetic layer 27 preferably has ahigher flux density. In the embodiment the magnetic layer 27 is made ofCoFeN having a saturation flux density of 2.4 T by way of example.

Next, etching masks 28 a and 28 b are formed on the magnetic layer 27.The etching mask 28 a is provided for forming an end portion fordefining the throat height in the magnetic layer 27, and is disposedabove the fourth layer 10 f. The etching mask 28 b is disposed above thecoupling layer 10 g. Each of the etching masks 28 a and 28 b has anundercut so that the bottom surface is smaller than the top surface inorder to facilitate lift-off that will be performed later. Such etchingmasks 28 a and 28 b may be formed by patterning a resist layer made upof two stacked organic films, for example.

FIG. 10A and FIG. 10B illustrate the following step. In the step themagnetic layer 27 is selectively etched by ion beam etching, forexample, through the use of the etching masks 28 a and 28 b. A magneticlayer 30 ap and a coupling layer 30 b are thereby made up of portions ofthe magnetic layer 27 remaining under the etching masks 28 a and 28 bafter the etching.

The magnetic layer 30 ap is disposed adjacent to the write gap layer 26.The magnetic layer 30 ap is patterned later to be a throat heightdefining layer 30 a. At this point the magnetic layer 30 ap has a widthgreater than the write track width. The magnetic layer 30 ap has an endportion 30 al that defines the throat height. The coupling layer 30 b isdisposed on top of the coupling layer 10 g. The above-mentioned etchingmay be performed such that the direction in which ion beams move formsan angle in a range of 0 to 20 degrees inclusive with respect to thedirection orthogonal to the top surface of the first layer 10 a. Next,to remove deposits on the sidewalls of the magnetic layer 27 after theetching, another etching is performed such that the direction in whichion beams move forms an angle in a range of 60 to 75 degrees inclusivewith respect to the direction orthogonal to the top surface of the firstlayer 10 a. By etching the magnetic layer 27 in such a manner, the endportion 30 al for defining the throat height is formed to be nearlyorthogonal to the top surface of the first layer 10 a. The throat heightis thereby defined with accuracy.

The magnetic layer 27 may be etched in the following manner. A mask isformed on the magnetic layer 27 by frame plating, for example. Next, themagnetic layer 27 is etched by reactive ion etching, for example, usingthe mask. A halogen gas such as Cl₂ or a mixture of BCl₃ and Cl₂ isutilized for the etching. The magnetic layer 27 is preferably etched ata temperature of 50° C. or higher so that the etching rate is increased.More preferably, the temperature falls within the range of 200 to 300°C. inclusive so that the etching is more successfully performed. It ispreferred to use a gas containing a halogen gas and O₂ or CO₂ foretching the magnetic layer 27. The halogen gas may be a gas containingat least one of Cl₂ and BCl₃. Through the use of the mixture of O₂ and ahalogen gas containing Cl₂, the profile of the magnetic layer 27 thathas been etched is controlled with accuracy. If the mixture of O₂ and ahalogen gas containing Cl₂ and BCl₃ is used, in particular, deposites ofmolecules of the halogen gas on the surface of the layered structurewill be removed so that the surface of the layered structure is madevery clean.

The rate of etching the magnetic layer 27 is higher if a gas containingCl₂ and CO₂, a gas containing Cl₂, BCl₃ and CO₂, or a gas containingBCl₃, Cl₂, O₂ and CO₂ is used, compared to the case in which a gas thatdoes not contain CO₂ is used. As a result, the etching selectivity ofthe magnetic layer 27 to the etching mask is increased by 30 to 50%.

After the magnetic layer 27 is etched, the write gap layer 26 isselectively etched and furthermore, the fourth layer 10 f is selectivelyetched, each by ion beam etching, for example, using the etching masks28 a and 28 b. The fourth layer 10 f is etched to a depth somewhere in amiddle of the thickness of the fourth layer 10 f. The depth to which thefourth layer 10 f is etched preferably falls within a range of 0.1 to0.4 μm inclusive, and more preferably 0.1 to 0.3 μm inclusive.

Through the above-mentioned etching of the fourth layer 10 f, a firstsurface 10A and a second surface 10B are formed on a surface of thebottom pole layer 10 facing toward the write gap layer 26. The firstsurface 10A includes an end located in the air bearing surface and theother end located opposite to the air bearing surface. The secondsurface 10B is disposed away from the air bearing surface. The firstsurface 10A is disposed adjacent to the write gap layer 26. There is adifference in level between the first surface 10A and the second surface10B, so that the second surface 10B is located farther from the top polelayer 30 than the first surface 10A.

Next, a first nonmagnetic layer 31 made of a nonmagnetic material isformed by lift-off. That is, the nonmagnetic layer 31 having a thicknessof 0.2 to 0.8 μm is formed to cover the entire top surface of thelayered structure while the etching masks 28 a and 28 b are leftunremoved. The nonmagnetic layer 31 is formed in a self-aligned mannersuch that the etched portions of the magnetic layer 27, the write gaplayer 26 and the fourth layer 10 f are filled with the nonmagnetic layer31. The nonmagnetic layer 31 is preferably formed such that the topsurface thereof is located in nearly the same level as the top surfaceof the magnetic layer 30 ap. The nonmagnetic layer 31 may be made of aninsulating material such as alumina.

FIG. 11A and FIG. 11B illustrate the following step. In the step theetching masks 28 a and 28 b are lifted off, and the top surfaces of themagnetic layer 30 ap, the coupling layer 30 b and the nonmagnetic layer31 are then polished and flattened by CMP, for example. In FIG. 11A andFIG. 11B numeral 32 indicates the level in which polishing is stopped.The depth to which the polishing is performed falls within a range of 10to 50 nm inclusive, for example.

FIG. 12A and FIG. 12B illustrate the following step. In the step asecond magnetic layer 33 made of a magnetic material and having athickness of 0.1 to 0.3 μm is formed by sputtering, for example, tocover the entire top surface of the layered structure. The magneticlayer 33 is made of a high saturation flux density material such asCoFeN, FeAlN, FeN, FeCo or FeZrN. The magnetic layer 33 is preferablyhas a high saturation flux density. In the embodiment the magnetic layer33 is made of CoFeN having a saturation flux density of 2.4 T, by way ofexample.

Next, etching masks 34 a and 34 b are formed on the magnetic layer 33.The etching mask 34 a is a mask for forming an end portion of themagnetic layer 33 opposite to the air bearing surface. The mask 34 a isdisposed above the magnetic layer 30 ap. The etching mask 34 b isdisposed above the coupling layer 30 b. Each of the etching masks 34 aand 34 b has an undercut so that the bottom surface is smaller than thetop surface in order to facilitate lift-off that will be performedlater. Such etching masks 34 a and 34 b may be formed by patterning aresist layer made up of two stacked organic films, for example.

FIG. 13A and FIG. 13B illustrate the following step. In the step themagnetic layer 33 is selectively etched by ion beam etching, forexample, through the use of the etching masks 34 a and 34 b. A magneticlayer 30 cp and a coupling layer 30 d are made up of portions of themagnetic layer 33 remaining under the etching masks 34 a and 34 b afterthe etching. The coupling layers 30 b and 30 d together with thecoupling layers 10 c, 10 e and 10 g make up the coupling section 43.

The magnetic layer 30 cp is disposed on a side of the magnetic layer 30ap farther from the write gap layer 26. The magnetic layer 30 cp will bepatterned to be an intermediate layer 30 c. At this time the magneticlayer 30 cp has a width greater than the write track width. The magneticlayer 30 cp has an end portion 30 cl located opposite to the air bearingsurface. The coupling layer 30 d is disposed on the coupling layer 30 b.The magnetic layer 33 may be etched through a method similar to themethod of etching the magnetic layer 27, for example.

Next, a second nonmagnetic layer 35 made of a nonmagnetic material isformed by lift-off. That is, the nonmagnetic layer 35 having a thicknessof 0.2 to 0.4 μm is formed to cover the entire top surface of thelayered structure while the etching masks 34 a and 34 b are leftunremoved. The nonmagnetic layer 35 is formed in a self-aligned mannersuch that the etched portions of the magnetic layer 33 are filled withthe nonmagnetic layer 35. The nonmagnetic layer 35 is preferably formedsuch that the top surface thereof is located in nearly the same level asthe top surface of the magnetic layer 30 cp. The nonmagnetic layer 35may be made of an insulating material such as alumina.

FIG. 14A and FIG. 14B illustrate the following step. In the step theetching masks 34 a and 34 b are lifted off, and the top surfaces of themagnetic layer 30 cp, the coupling layer 30 d and the nonmagnetic layer35 are then polished and flattened by CMP, for example. In FIG. 14A andFIG. 14B numeral 36 indicates the level in which polishing is stopped.The depth to which the polishing is performed falls within a range of 10to 50 nm inclusive, for example.

FIG. 15A and FIG. 15B illustrate the following step. In the step amagnetic layer 37 made of a magnetic material and having a thickness of0.1 to 0.3 μm is formed by sputtering, for example, to cover the entiretop surface of the layered structure. The magnetic layer 37 is made of ahigh saturation flux density material such as CoFeN, FeAlN, FeN, FeCo orFeZrN.

Next, a yoke portion layer 30 f made of a magnetic material is formed byframe plating, for example, on the magnetic layer 37, wherein themagnetic layer 37 is used as an electrode and a seed layer. The yokeportion layer 30 f has a thickness of 3 to 4 μm, for example. The yokeportion layer 30 f may be made of CoNiFe or FeCo having a saturationflux density of 2.3 T, for example. The yoke portion layer 30 f isdisposed to extend from a region corresponding to the magnetic layer 30cp to a region corresponding to the coupling layer 30 d.

FIG. 16A and FIG. 16B illustrate the following step. In the step themagnetic layers 37, 30 cp and 30 ap and the write gap layer 26 areselectively etched by ion beam etching, for example, using the yokeportion layer 30 f as an etching mask. The magnetic layer 37 thus etchedis a yoke portion layer 30 e. The plane geometry of the yoke portionlayer 30 e is the same as that of the yoke portion layer 30 f. Themagnetic layer 30 cp thus etched is the intermediate layer 30 c. Themagnetic layer 30 ap thus etched is a throat height defining layer 30 a.After the above-mentioned etching is performed, the yoke portion layer30 f has a thickness of 1 to 2 μm, for example. The top pole layer 30 ismade up of the throat height defining layer 30 a, the intermediate layer30 c, the coupling layers 30 b and 30 d, and the yoke portion layers 30e and 30 f.

As shown in FIG. 19, the layered structure made up of the yoke portionlayers 30 e and 30 f includes a second track width defining portion 30Aand a yoke portion 30B. The second track width defining portion 30A hasan end located in the air bearing surface 42 and the other end locatedaway from the air bearing surface. The yoke portion 30B is coupled tothe other end of the track width defining portion 30A. The track widthdefining portion 30A has a uniform width. The track width definingportion 30A initially has a width of about 0.15 to 0.2 μm, for example.The yoke portion 30B is equal in width to the track width definingportion 30A at the interface with the track width defining portion 30A.The yoke portion 30B gradually increases in width as the distance fromthe track width defining portion 30A increases, and then maintains aspecific width to the end.

Next, although not shown, a photoresist mask having an opening aroundthe track width defining portion 30A is formed. Using the photoresistmask and the track width defining portion 30A as masks, a portion of thefourth layer 10 f is etched by ion beam etching, for example. Thisetching may be performed such that the direction in which ion beams moveforms an angle in a range of 35 to 55 degrees inclusive, for example,with respect to the direction orthogonal to the top surface of the firstlayer 10 a. The depth to which the fourth layer 10 f is etched ispreferably 0.1 to 0.4 μm, and more preferably 0.1 to 0.3 μm. If thedepth to which the etching is performed is 0.5 μm or greater, theoccurrences of side write or side erase increase.

A trim structure is thereby formed, wherein a portion of the fourthlayer 10 f, the write gap layer 26, the throat height defining layer 30a, the intermediate layer 30 c, and the track width defining portion 30Ahave the same widths in the air bearing surface. The trim structuresuppresses an increase in the effective recording track width due toexpansion of a magnetic flux generated during writing in a narrow track.

Next, sidewalls of the portion of the fourth layer 10 f, the write gaplayer 26, the throat height defining layer 30 a, the intermediate layer30 c and the track width defining portion 30A are etched by ion beametching, for example, to reduce the widths of these layers in the airbearing surface down to 0.1 μm, for example. This etching may beperformed such that the direction in which ion beams move forms an anglein a range of 40 to 75 degrees inclusive, for example, with respect tothe direction orthogonal to the top surface of the first layer 10 a.

FIG. 17A and FIG. 17B illustrate the following step. In the step theovercoat layer 38 made of alumina, for example, and having a thicknessof 20 to 30 μm is formed so as to cover the entire top surface of thelayered structure. The surface of the overcoat layer 38 is flattened,and electrode pads (not shown) are formed thereon. Finally, the sliderincluding the foregoing layers is lapped to form the air bearing surface42. The thin-film magnetic head including the read and write heads isthus completed.

According to the embodiment, the following method may be employed toform the yoke portion layers as shown in FIG. 20A and FIG. 20B, insteadof forming the yoke portion layers 30 e and 30 f by frame plating asdescribed with reference to FIG. 15A and FIG. 15B. FIG. 20A is a crosssection orthogonal to the air bearing surface and the top surface of thesubstrate. FIG. 20B is a cross section of the pole portions parallel tothe air bearing surface. In this method a magnetic layer made of amagnetic material and having a thickness of 1.0 to 1.5 μm is formed bysputtering on the entire top surface of the layered structure includingthe flattened top surfaces of the magnetic layer 30 cp, the couplinglayer 30 d and the nonmagnetic layer 35. The magnetic layer may be madeof CoFeN or FeCo having a saturation flux density of 2.4 T. Next, aninsulating layer made of alumina, for example, and having a thickness of0.3 to 2.0 μm is formed on the magnetic layer. Next, an etching maskhaving a thickness of 0.5 to 1.0 μm, for example, is formed by frameplating, for example, on the insulating layer. The etching mask may bemade of NiFe (45 weight % Ni and 55 weight % Fe), CoNiFe (67 weight %Co, 15 weight % Ni and 18 weight % Fe) having a saturation flux densityof 1.9 to 2.1 T, or FeCo (60 weight % Fe and 40 weight % Co) having asaturation flux density of 2.3 T. The plane geometry of the etching maskis the same as that of the yoke portion layer 30 f The etching mask hasa portion for defining the track width. This portion has a width of 0.1to 0.2 μm, for example.

Next, the insulating layer is selectively etched by reactive ionetching, for example, using the etching mask. A halogen gas such as Cl₂or a mixture of BCl₃ and Cl₂ is utilized for this etching. The etchingmask may be either removed or left unremoved through the etching. If theetching mask is removed, it is possible to perform etching of themagnetic layer later with more accuracy. Next, the magnetic layer isselectively etched by reactive ion etching, for example, using theinsulating layer as another etching mask 39. The magnetic layer ispreferably etched at a temperature of 50° C. or higher so that theetching rate is increased. More preferably, the temperature falls withinthe range of 200 to 300° C. inclusive so that the etching is moresuccessfully performed. The magnetic layer that has been etched servesas a yoke portion layer 30 g. In this example the top pole layer 30 ismade up of the throat height defining layer 30 a, the intermediate layer30 c, the coupling layers 30 b and 30 d, and the yoke portion layer 30g.

Alternatively, as shown in FIG. 20A and FIG. 20B, it is possible thatthe etching mask 39 is formed on the magnetic layer to be the yokeportion layer 30 g as described above, and the magnetic layer 30 ap (SeeFIG. 15A and FIG. 15B.), the magnetic layer 30 cp, and the magneticlayer to be the yoke portion layer 30 g are selectively etched byreactive ion etching, using the etching mask 39 to form the yoke portionlayer 30 g, the intermediate layer 30 c, and the throat height defininglayer 30 a. In this case, the write gap layer 26 is preferably made of anonmagnetic inorganic material such as alumina, silicon carbide (SiC),or aluminum nitride (AlN). It is thereby possible that the etching rateof the write gap layer 26 is lower than that of the magnetic layer whenthe magnetic layer made of a magnetic material including at least ironthat is one of the group consisting of iron and cobalt, such as CoFeN orFeCo, is etched by reactive ion etching. As a result, the sidewalls ofthe magnetic layer that has been etched form an angle of nearly 90degrees with respect to the top surface of the write gap layer 26. It isthereby possible to define the track width with accuracy.

This feature will now be described in detail. For example, a case isconsidered wherein the magnetic layer including at least iron that isone of the group consisting of iron and cobalt is etched by reactive ionetching, using the etching mask 39 made of alumina. In this case, aproduct formed through a plasma reaction between Cl₂ of the etching gasand iron or iron and cobalt of the magnetic layer deposits on thesidewalls of the magnetic layer that has been etched. As a result,during the etching, until the bottom portion formed through the etchingreaches the neighborhood of the write gap layer 26, the magnetic layeretched is likely to have the shape in which the width thereof increasesas the distance to the lower portion of the magnetic layer decreases.However, the amount of the above-mentioned product formed through theplasma reaction extremely decreases when the bottom portion formedthrough the etching reaches the neighborhood of the write gap layer 26.If the etching is further continued after the bottom portion reaches thewrite gap layer 26, portions of the sidewalls of the magnetic layeretched, the portions being near the bottom portion, are then etched, andthe magnetic layer etched finally has a shape in which the sidewalls ofthe magnetic layer etched form an angle of nearly 90 degrees withrespect to the top surface of the write gap layer 26. To form themagnetic layer having such a shape, it is required that the othermagnetic layer below the write gap layer 26 would not be exposed duringthe etching until the magnetic layer etched has the above-mentionedshape. This is because, if the other magnetic layer below the write gaplayer 26 is exposed during the etching, a product of a plasma reactionformed through the etching of the magnetic layer exposed deposits on thesidewalls of the magnetic layer etched.

Here, if the write gap layer 26 is made of a nonmagnetic inorganicmaterial such as alumina, silicon carbide (SiC), or aluminum nitride(AlN), the etching rate of the write gap layer 26 is lower than that ofthe magnetic layer. It is thereby possible to prevent the other magneticlayer below the write gap layer 26 from being exposed during the etchinguntil the magnetic layer etched has the above-mentioned shape. As aresult, the sidewalls of the magnetic layer that has been etched form anangle of nearly 90 degrees with respect to the top surface of the writegap layer 26.

The following are preferred conditions for etching the magnetic layer byreactive ion etching as described above. The pressure in the chamber(the degree of vacuum) is preferably 0.1 to 1.0 Pa. The temperature atwhich the etching is performed is preferably 200 to 300° C. The etchinggas preferably includes Cl₂, and more preferably includes BCl₃ and CO₂,in addition to Cl₂. The flow rate of Cl₂ of the etching gas ispreferably 100 to 300 ccm. The flow rate of BCl₃ of the etching gas ispreferably 50% of the flow rate of Cl₂ or lower. If the flow rate ofBCl₃ is higher than 50% of the flow rate of Cl₂, alumina is likely to beetched. The flow rate of CO₂ of the etching gas is preferably 10% of theflow rate of Cl₂ or lower. If the flow rate of CO₂ is higher than 10% ofthe flow rate of Cl₂, the sidewalls of the magnetic layer form a greaterangle with respect to the direction orthogonal to the top surface of thewrite gap layer 26. The substrate bias for the etching is preferably 150to 500 W.

For etching the magnetic layer by reactive ion etching as describedabove, the etching mask 39 is preferably made of a nonmagnetic inorganicmaterial such as alumina, silicon carbide (SiC), or aluminum nitride(AlN), which is similar to the write gap layer 26. This is because, asin the case of the write gap layer 26, the etching rate of the etchingmask 39 is lower than that of the magnetic layer when the magnetic layermade of a magnetic material including at least iron that is one of thegroup consisting of iron and cobalt, such as CoFeN or FeCo, is etched byreactive ion etching.

If the magnetic layer is etched by reactive ion etching and the yokeportion layer 30 g, the intermediate layer 30 c and the throat heightdefining layer 30 a are thereby formed as described above, the write gaplayer 26 is then etched by ion beam etching, for example, using thethroat height defining layer 30 a as a mask. Next, a photoresist mask(not shown) having an opening around the track width defining portion30A is formed. A portion of the fourth layer 10 f is etched by ion beametching, for example, using the photoresist mask and the track widthdefining portion 30A as masks. A trim structure is thereby formed.

According to the embodiment, the second coil 19 may be made by thefollowing method, instead of the method described with reference to FIG.3A to FIG. 6A, and FIG. 3B to FIG. 6B. In this method the insulatingfilm 17 is formed in addition to the state shown in FIG. 2A and FIG. 2Bto cover the entire top surface of the layered structure. Next, anelectrode film is formed to cover the entire top surface of the layeredstructure. On the electrode film the conductive layer 19 p made of ametal such as Cu and having a thickness of 3 to 4 μm, for example, isformed by frame plating, for example. Next, portions of the electrodefilm except the portion below the conductive layer 19 p are removed byion beam etching, for example. Next, an insulating layer made ofalumina, for example, and having a thickness of 3 to 5 μm is formed tocover the entire top surface of the layered structure. The insulatinglayer is then polished by CMP, for example, so that the second layer 10b, the coupling layer 10 c and the first coil 13 are exposed. The secondcoil 19 is thereby made up of the conductive layer 19 p and theelectrode film remaining in the space between the second layer 10 b andthe first coil 13, the space between the turns of the first coil 13, andthe space between the coupling layer 10 c and the first coil 13.

The thin-film magnetic head according to the present embodimentcomprises the air bearing surface 42 serving as a medium facing surfacethat faces toward a recording medium. The magnetic head furthercomprises the read head and the write head (the induction-typeelectromagnetic transducer). 49 The read head includes: the MR element 5located near the air bearing surface 42; the bottom shield layer 3 andthe top shield layer 8 for shielding the MR element 5; the bottom shieldgap film 4 located between the MR element 5 and the bottom shield layer3; and the top shield gap film 7 located between the MR element 5 andthe top shield layer 8. The portions of the bottom shield layer 3 andthe top shield layer 8 located on a side of the air bearing surface 42are opposed to each other with the MR element 5 in between.

The write head comprises the bottom pole layer 10 and the top pole layer30 that are magnetically coupled to each other and include the poleportions opposed to each other and located in the regions of the polelayers on the side of the air bearing surface 42. The write head furthercomprises: the write gap layer 26 disposed between the pole portion ofthe bottom pole layer 10 and the pole portion of the top pole layer 30;and the coils 13 and 19. The coils 13 and 19 are provided such that atleast part thereof is disposed between the bottom pole layer 10 and thetop pole layer 30 and insulated from the bottom pole layer 10 and thetop pole layer 30. The bottom pole layer 10 and the top pole layer 30 ofthe present embodiment correspond to the first pole layer and the secondpole layer of the invention, respectively. 50 The bottom pole layer 10includes the first layer 10 a, the second layer 10 b, the third layer 10d, the fourth layer 10 f, and the coupling layers 10 c, 10 e and 10 g.The first layer 10 a is disposed to be opposed to the coils 13 and 19.The second layer 10 b is disposed near the air bearing surface 42 andconnected to the first layer 10 a in such a manner that the second layer10 b protrudes closer toward the top pole layer 30 than the first layer10 a. The third layer 10 d is disposed near the air bearing surface 42and connected to the second layer 10 b in such a manner that the thirdlayer 10 d protrudes closer toward the top pole layer 30 than the secondlayer 10 b. The fourth layer 10 f is disposed near the air bearingsurface 42 and connected to the third layer 10 d in such a manner thatthe fourth layer 10 f protrudes closer toward the top pole layer 30 thanthe third layer 10 d.

The surface of the bottom pole layer 10 closer to the write gap layer 26incorporates the first surface 10A and the second surface 10B. The firstsurface 10A includes the end located in the air bearing surface 42 andthe other end located farther from the air bearing surface 42. Thesecond surface 10B is disposed away from the air bearing surface 42. Thefirst surface 10A is disposed adjacent to the write gap layer 26. Thereis a difference in level between the first surface 10A and the secondsurface 10B, so that the second surface 10B is located farther from thetop pole layer 30 than the first surface 10A.

The top pole layer 30 incorporates the throat height defining layer 30 athat is disposed adjacent to the write gap layer 26 and includes the endportion 30 al for defining the throat height. The top pole layer 30further incorporates: the intermediate layer 30 c disposed on a side ofthe throat height defining layer 30 a farther from the write gap layer26; the yoke portion layers 30 e and 30 f disposed on a side of theintermediate layer 30 c farther from the throat height defining layer 30a; and the coupling layers 30 b and 30 d. The yoke portion layers 30 eand 30 f include the track width defining portion 30A for defining thetrack width.

The width of each of the throat height defining layer 30 a, theintermediate layer 30 c, and the track width defining portion 30A takenin the air bearing surface 42 is equal to the track width. The length ofthe intermediate layer 30 c is greater than the length of the throatheight defining layer 30 a, and the length of the yoke portion layers 30e and 30 f is greater than the length of the intermediate layer 30 c,each of the lengths being taken in the direction orthogonal to the airbearing surface 42. The intermediate layer 30 c and the yoke portionlayers 30 e and 30 f are flat layers.

The throat height defining layer 30 a includes an end portion located inthe air bearing surface 42 and the other end portion 30 al locatedfarther from the air bearing surface 42. The throat height defininglayer 30 a corresponds to the first layer of the second pole layer ofthe invention. Each of the yoke portion layers 30 e and 30 f correspondsto the second layer of the second pole layer of the invention. Thecoupling layers 10 c, 10 e, 10 g, 30 b and 30 d make up the couplingsection 43 for magnetically coupling the bottom pole layer 10 to the toppole layer 30.

The fourth layer 10 f of the bottom pole layer 10 has a portion thatfaces toward the throat height defining layer 30 a of the top pole layer30, the write gap layer 26 being disposed in between. This portion isthe pole portion of the bottom pole layer 10. The throat height defininglayer 30 a is the pole portion of the top pole layer 30. As shown inFIG. 17A, throat height TH is the distance between the air bearingsurface 42 and the end portion 30 al of the throat height defining layer30 a. Zero throat height level TH0 is the level of the end portion 30 alof the throat height defining layer 30 a. Each of the fourth layer 10 fand the throat height defining layer 30 a preferably has a saturationflux density of 2.4 T or greater.

As shown in FIG. 18, the thin-film coil of the embodiment includes thefirst coil 13, the second coil 19 and the connecting layer 21. The firstcoil 13 has turns part of which is disposed between the second layer 10b and the coupling layer 10 c. The second coil 19 has turns at leastpart of which is disposed between turns of the first coil 13. Theconnecting layer 21 is disposed on a side of the third layer 10 d andconnects the coil 13 to the coil 19 in series. Part of the turns of thesecond coil 19 is disposed between the second layer 10 b and thecoupling layer 10 c, too. The coils 13 and 19 are both flat whorl-shapedand disposed around the coupling portion 43. The coils 13 and 19 areboth wound clockwise from the outer end to the inner end. The connectinglayer 21 connects the connecting portion 13 a of the coil 13 to theconnecting portion 19 b of the coil 19 at the minimum distance. Theconnecting layer 21 has a thickness smaller than the thickness of eachof the coils 13 and 19. The coils 13 and 19 and the connecting layer 21are all made of a metal, such as Cu. The thin-film coil of theembodiment has seven turns although the invention is not limited to theseven-turn coil.

The method of manufacturing the thin-film magnetic head of theembodiment comprises the steps of: forming the bottom pole layer 10;forming the thin-film coil (made up of the coils 13 and 19 and theconnecting layer 21) on the bottom pole layer 10; and forming the writegap layer 26 on the pole portion of the bottom pole layer 10.

The method further comprises the steps of: forming the magnetic layer 27on the write gap layer 26 for forming the throat height defining layer30 a; forming the etching mask 28 a on the magnetic layer 27 for formingthe end portion 30 al for defining the throat height in the magneticlayer 27; and forming the end portion 30 al for defining the throatheight in the magnetic layer 30 ap, the magnetic layer 30 ap being madeup of the magnetic layer 27 etched, and forming the first surface 10Aand the second surface 10B of the surface of the bottom pole layer 10closer to the write gap layer 26, by selectively etching the magneticlayer 27, the write gap layer 26 and the fourth layer 10 f through theuse of the etching mask 28 a.

The method of the embodiment further comprises the steps of: forming thenonmagnetic layer 31 so as to fill the etched portions of the magneticlayer 27, the gap layer 26 and the fourth layer 10 f while the mask 28 ais left unremoved; removing the mask 28 a after the nonmagnetic layer 31is formed; and flattening the top surfaces of the magnetic layer 30 apand the nonmagnetic layer 31, the magnetic layer 30 ap being made up ofthe magnetic layer 27 etched, by polishing such as CMP, after the mask28 a is removed.

The method of the embodiment further comprises the steps of: forming themagnetic layer 33 on the flattened top surfaces of the magnetic layer 30ap and the nonmagnetic layer 31 for forming the intermediate layer 30 c;forming the etching mask 34 a on the magnetic layer 33 for making theend portion 30 cl of the magnetic layer 33 located opposite to the airbearing surface 42; and forming the end portion 30 cl of the magneticlayer 30 cp by selectively etching the magnetic layer 33 through the useof the etching mask 34 a, the magnetic layer 30 cp being made up of themagnetic layer 33 that has been etched.

The method further comprises the steps of: forming the nonmagnetic layer35 so as to fill the etched portion of the magnetic layer 33 while themask 34 a is left unremoved; removing the mask 34 a after thenonmagnetic layer 35 is formed; and flattening the top surfaces of themagnetic layer 30 cp and the nonmagnetic layer 35, the magnetic layer 30cp being made up of the magnetic layer 33 etched, by polishing such asCMP, after the mask 34 a is removed.

The method further comprises the steps of: forming the yoke portionlayers 30 e and 30 f on the flattened top surfaces of the magnetic layer30 cp and the nonmagnetic layer 35; and etching the magnetic layers 30cp and 30 ap, the write gap layer 26 and a portion of the fourth layer10 f of the bottom pole layer 10 to align with the width of the trackwidth defining portion 30A through the use of the track width definingportion 30A of the yoke portion layers 30 e and 30 f as a mask. Throughthis step the magnetic layer 30 cp is patterned to form the intermediatelayer 30 c, and the magnetic layer 30 ap is patterned to form the throatheight defining layer 30 a. In addition, each of the portion of thefourth layer 10 f, the write gap layer 26, the throat height defininglayer 30 a, the intermediate layer 30 c, and the track width definingportion 30A is made to have a width taken in the air bearing surface 42that is equal to the track width.

According to the embodiment, in the step of forming the end portion 30al for defining the throat height in the magnetic layer 30 ap byselectively etching the magnetic layer 27, the magnetic layer 30 apbeing made up of the magnetic layer 27 etched, the write gap layer 26and the fourth layer 10 f of the bottom pole layer 10 are selectivelyetched to the depth somewhere in the middle of the thickness of thefourth layer 10 f.

According to the embodiment, each of the bottom pole layer 10 and thetop pole layer 30 has the stepped portion for increasing the distancebetween the two pole layers 10 and 30 in a region farther from the airbearing surface 42 than the zero throat height level TH0. Therefore,according to the embodiment, the distance between the two pole layers 10and 30 in the region farther from the air bearing surface 42 than thezero throat height level TH0 is increased without making a very greatdifference in level between the first surface 10A and the second surface10B of the bottom pole layer 10. As a result, according to theembodiment, it is possible to prevent an extreme reduction in the volumeof the portion of the bottom pole layer 10 sandwiched between the sideportions forming the trim structure, and to prevent a sudden decrease inthe cross-sectional area of the magnetic path near the interface betweenthe above-mentioned portion of the bottom pole layer 10 and the otherportion.

According to the embodiment, the throat height defining layer 30 a, theintermediate layer 30 c and the yoke portion layers 30 e and 30 f arestacked one by one on the write gap layer 26. Each of the throat heightdefining layer 30 a, the intermediate layer 30 c and the track widthdefining portion 30A has a width taken in the air bearing surface 42that is equal to the track width. In addition, the length of theintermediate layer 30 c taken in the direction orthogonal to the airbearing surface 42 is greater than the length of the throat heightdefining layer 30 a. The length of the yoke portion layers 30 e and 30 ftaken in the direction orthogonal to the air bearing surface 42 isgreater than the length of the intermediate layer 30 c. According to theembodiment, these features achieve an increase in the distance betweenthe top pole layer 30 and the bottom pole layer 10 in the region fartherfrom the air bearing surface 42 than the zero throat height level TH0.In addition, the cross-sectional area of the magnetic path of the toppole layer 30 near the air bearing surface 42 is made to graduallychange. According to the embodiment, these features prevent saturationand leakage of flux halfway through the magnetic path. The overwriteproperty is thereby improved.

According to the embodiment, it is possible to prevent an extremereduction in the volume of the portion of the bottom pole layer 10sandwiched between the side portions forming the trim structure. As aresult, it is possible to prevent leakage of magnetic flux from theneighborhood of the bottom of the stepped portion of the trim structurethat belongs to the end face of the bottom pole layer 10 exposed fromthe air bearing surface 42 toward the recording medium, in particular.It is thereby possible to prevent side write and side erase.

In the air bearing surface 42 the throat height defining layer 30 a, theintermediate layer 30 c and the yoke portion layers 30 e and 30 f haveequal widths. Therefore, there is no sudden variation in width in theend face of the top pole layer 30 exposed from the air bearing surface42. As a result, an amount of flux leakage from the end face of the toppole layer 30 exposed from the air bearing surface 42 is small, and itis possible to prevent a reduction in overwrite property and to preventthe occurrences of side write and side erase.

According to the embodiment, the nonmagnetic layer 31 is formed bylift-off so as to fill the etched portions of the magnetic layer 27, thewrite gap layer 26 and the fourth layer 10 f It is therefore possible toflatten the top surfaces of the throat height defining layer 30 a andthe nonmagnetic layer 31 by a small amount of polishing. It is therebypossible to determine the thickness of the pole portion of the top polelayer 30 with accuracy. Similarly, according to the embodiment, thenonmagnetic layer 35 is formed by lift-off so as to fill the etchedportion of the magnetic layer 33. It is therefore possible to flattenthe top surfaces of the intermediate layer 30 c and the nonmagneticlayer 35 by a small amount of polishing. It is thereby possible todetermine the thickness of the intermediate layer 30 c with accuracy.Owing to these features, according to the embodiment, the thickness ofthe top pole layer 30 exposed from the air bearing surface 42 iscontrolled with accuracy. As a result, the writing characteristics ofthe thin-film magnetic head are easily controlled with accuracy. Thenonmagnetic layer 31 may be formed such that the top surface thereof isdisposed in the level almost the same as the level of the top surface ofthe throat height defining layer 30 a. It is thereby possible to omitthe step of flattening the top surfaces of the magnetic layer 30 ap andthe nonmagnetic layer 31 by polishing. Similarly, the nonmagnetic layer35 may be formed such that the top surface thereof is disposed in thelevel almost the same as the level of the top surface of theintermediate layer 30 c. It is thereby possible to omit the step offlattening the top surfaces of the magnetic layer 30 cp and thenonmagnetic layer 35 by polishing.

According to the embodiment, the yoke portion layers 30 e and 30 f ofthe top pole layer 30 are flat layers formed on the nearly flat baselayer. As a result, according to the embodiment, it is possible to formthe track width defining portion 30A that is small in size withaccuracy. It is thereby possible to reduce the track width and improvethe writing density.

According to the embodiment, the second layer 10 b, the third layer 10d, the fourth layer 10 f and the top pole layer 30 may be made of a highsaturation flux density material. It is thereby possible to prevent asaturation of flux halfway through the magnetic path. To achieve this,it is particularly effective that the fourth layer 10 f and the throatheight defining layer 30 a are made of a high saturation flux densitymaterial having a saturation flux density of 2.4 T or greater. It isthereby possible to use the magnetomotive force generated by thethin-film coil for writing with efficiency. It is thus possible toachieve the write head having an excellent overwrite property.

According to the embodiment, the first coil 13 is formed on the firstlayer 10 a having an entirely flat top surface. It is thus possible toform the first coil 13 that is thick but small in size with accuracy.According to the embodiment, the second coil 19 is formed such that atleast part of the turns of the second coil 19 is disposed between theturns of the first coil 13. It is thereby possible to form the secondcoil 19 that is thick but small in size with accuracy, too. According tothe embodiment, it is the thin insulating film 17 that separates thesecond layer 10 b from the second coil 19, the turns of the first coil13 from the turns of the second coil 19, and the coupling layer 10 cfrom the second coil 19. It is thereby possible that the space betweenthe second layer 10 b and the second coil 19, the space between theturns of the first coil 13 and the turns of the second coil 19, and thespace between the coupling layer 10 c and the second coil 19 are madevery small.

The foregoing features of the embodiment allow the coils 13 and 19 to bethick and the yoke length to be short. It is thereby possible to reducethe resistance of the thin-film coil while the yoke length is reduced,that is, the magnetic path length is reduced. As a result, according tothe embodiment of the invention, it is possible to achieve the thin-filmmagnetic head having a reduced magnetic path length and thus havingexcellent writing characteristics in a high frequency band, and havingthe thin-film coil with a low resistance.

According to the embodiment, an outer portion of the thin-film coil isdisposed adjacent to the second layer 10 b, the thin insulating film 17being located in between. That is, the thin-film coil is disposed nearthe air bearing surface 42. As a result, according to the embodiment, itis possible to utilize the magnetomotive force generated by thethin-film coil for writing with efficiency. It is thereby possible toachieve the write head having an excellent overwrite property.

According to the embodiment, a coil for connecting the coil 13 to thecoil 19 in series may be provided in place of the connecting layer 21.It is thereby possible to increase the number of turns of the thin-filmcoil without increasing the yoke length while an increase in resistanceof the thin-film coil is prevented.

Second Embodiment

Reference is now made to FIG. 21A to FIG. 27A and FIG. 21B to FIG. 27Bto describe a method of manufacturing a thin-film magnetic head of asecond embodiment of the invention. FIG. 21A to FIG. 27A are crosssections orthogonal to the air bearing surface and the top surface ofthe substrate. FIG. 21B to FIG. 27B are cross sections of the poleportions parallel to the air bearing surface.

The method of manufacturing the thin-film magnetic head of the secondembodiment includes the steps up to the step of forming the insulatinglayer 25 as shown in FIG. 8A and FIG. 8B that are the same as those ofthe first embodiment.

FIG. 21A and FIG. 21B illustrate the following step. In the step thewrite gap layer 26 having a thickness of 0.07 to 0.1 μm is formed tocover the entire top surface of the layered structure. The write gaplayer 26 may be made of an insulating material such as alumina or anonmagnetic metal such as Ru, NiCu, Ta, W or NiB. Next, a portion of thewrite gap layer 26 corresponding to the coupling layer 10 g isselectively etched.

Next, the etching mask 28 a is formed on the write gap layer 26 and theetching mask 28 b is formed on the coupling layer 10 g. The etching mask28 a is provided for forming an end portion for defining the throatheight in the write gap layer 26, and is disposed above the fourth layer10 f. Each of the etching masks 28 a and 28 b has an undercut so thatthe bottom surface is smaller than the top surface in order tofacilitate lift-off that will be performed later. Such etching masks 28a and 28 b may be formed by patterning a resist layer made up of twostacked organic films, for example.

FIG. 22A and FIG. 22B illustrate the following step. In the step thewrite gap layer 26 is selectively etched and furthermore, the fourthlayer 10 f is selectively etched, each by ion beam etching, for example,using the etching masks 28 a and 28 b. The fourth layer 10 f is etchedto a depth somewhere in a middle of the thickness of the fourth layer 10f. The depth to which the fourth layer 10 f is etched preferably fallswithin a range of 0.1 to 0.4 μm inclusive, and more preferably 0.1 to0.3 μm inclusive. Through this etching, the end portion 26 a fordefining the throat height is formed in the write gap layer 26. Throughthe etching of the fourth layer 10 f, the first surface 10A and thesecond surface 10B having a difference in level are formed on a surfaceof the bottom pole layer 10 closer to the write gap layer 26.

Next, the nonmagnetic layer 31 made of a nonmagnetic material is formedby lift-off. That is, the nonmagnetic layer 31 having a thickness of 0.2to 0.8 μm is formed to cover the entire top surface of the layeredstructure while the etching masks 28 a and 28 b are left unremoved. Thenonmagnetic layer 31 is formed in a self-aligned manner such that theetched portions of the write gap layer 26 and the fourth layer 10 f arefilled with the nonmagnetic layer 31. The nonmagnetic layer 31 ispreferably formed such that the top surface thereof is located in nearlythe same level as the top surface of the write gap layer 26. Thenonmagnetic layer 31 may be made of an insulating material such asalumina.

FIG. 23A and FIG. 23B illustrate the following step. In the step theetching masks 28 a and 28 b are lifted off, and a magnetic layer 50 madeof a magnetic material and having a thickness of 0.1 to 0.2 μm is formedby sputtering, for example, on the entire top surface of the layeredstructure. According to the embodiment, the base layer of the magneticlayer 50 has projections and depressions so that the magnetic layer 50is made to have an uneven top surface, too. The magnetic layer 50 ismade of a high saturation flux density material such as CoFeN, FeAlN,FeN, FeCo or FeZrN. The magnetic layer 50 preferably has a saturationflux density of 2.4 T or greater. In the embodiment the magnetic layer50 is made of CoFeN having a saturation flux density of 2.4 T by way ofexample. The magnetic layer 50 is connected to the coupling layer 10 g.

Next, the top surface of the magnetic layer 50 is polished by CMP, forexample, and flattened. In FIG. 23A and FIG. 23B numeral 51 indicatesthe level in which the polishing is stopped. The polishing is performedto such an extent that the projections and depressions of the topsurface of the magnetic layer 50 are removed. The depth to which thepolishing is performed falls within a range of 10 to 50 nm inclusive,for example. This step of flattening may be omitted.

FIG. 24A and FIG. 24B illustrate the following step. In the step etchingmasks 52 a and 52 b are formed on the magnetic layer 50. The etchingmask 52 a is a mask for forming an end portion of the magnetic layer 50opposite to the air bearing surface. The mask 52 a is disposed above thegap layer 26. The etching mask 52 b is disposed above the coupling layer10 g. Each of the etching masks 52 a and 52 b has an undercut so thatthe bottom surface is smaller than the top surface in order tofacilitate lift-off that will be performed later. Such etching masks 52a and 52 b may be formed by patterning a resist layer made up of twostacked organic films, for example.

Next, the magnetic layer 50 is selectively etched by ion beam etching,for example, through the use of the etching masks 52 a and 52 b. Amagnetic layer 53 ap and a coupling layer 53 b are thereby made up ofportions of the magnetic layer 50 remaining under the etching masks 52 aand 52 b after the etching. The coupling layer 53 b is disposed abovethe coupling layer 10 g. The coupling layer 53 b together with thecoupling layers 10 c, 10 e and 10 g makes up the coupling section 43.

The magnetic layer 53 ap is disposed adjacent to the write gap layer 26and includes an end located in the air bearing surface 42 and the otherend located opposite to the air bearing surface 42. At this time themagnetic layer 53 ap has a width greater than the write track width.

Next, a nonmagnetic layer 54 made of a nonmagnetic material is formed bylift-off. That is, the nonmagnetic layer 54 having a thickness of 0.2 to0.3 μm is formed to cover the entire top surface of the layeredstructure while the etching masks 52 a and 52 b are left unremoved. Thenonmagnetic layer 54 is formed in a self-aligned manner such that theetched portion of the magnetic layer 50 is filled with the nonmagneticlayer 54. The nonmagnetic layer 54 is preferably formed such that thetop surface thereof is located in nearly the same level as the topsurface of the magnetic layer 53 ap. The nonmagnetic layer 54 may bemade of an insulating material such as alumina.

FIG. 25A and FIG. 25B illustrate the following step. In the step theetching masks 52 a and 52 b are lifted off, and the top surfaces of themagnetic layer 53 ap, the coupling layer 53 b and the nonmagnetic layer54 are then polished by CMP, for example, and flattened. In FIG. 25A andFIG. 25B numeral 55 indicates the level in which the polishing isstopped. The depth to which the polishing is performed falls within arange of 10 to 50 nm inclusive, for example.

FIG. 26A and FIG. 26B illustrate the following step. In the step amagnetic layer made of a magnetic material and having a thickness of 0.1to 0.3 μm is formed by sputtering, for example, on the entire topsurface of the layered structure. The magnetic layer is made of a highsaturation flux density material such as CoFeN, FeAlN, FeN, FeCo orFeZrN.

Next, a yoke portion layer 53 d made of a magnetic material is formed byframe plating, for example, on the magnetic layer, wherein the magneticlayer is used as an electrode and a seed layer. The yoke portion layer53 d has a thickness of 3 to 4 μm, for example. The yoke portion layer53 d may be made of CoNiFe or FeCo having a saturation flux density of2.3 T, for example. The yoke portion layer 53 d is disposed to extendfrom a region corresponding to the magnetic layer 53 ap to a regioncorresponding to the coupling layer 53 b.

Next, the write gap layer 26, the magnetic layer 53 ap, and the magneticlayer below the yoke portion layer 53 d are selectively etched by ionbeam etching, for example, using the yoke portion layer 53 d as anetching mask. The magnetic layer below the yoke portion layer 53 d thusetched is a yoke portion layer 53 c. The plane geometry of the yokeportion layer 53 c is the same as that of the yoke portion layer 53 d.The magnetic layer 53 ap thus etched is the magnetic layer 53 a thatcorresponds to the first layer of the invention. After theabove-mentioned etching is performed, the yoke portion layer 53 d has athickness of 1 to 2 μm, for example. The top pole layer 30 is made up ofthe magnetic layer 53 a, the coupling layer 53 b, and the yoke portionlayers 53 c and 53 d. The top pole layer 30 of the second embodiment hasa shape the same as the top pole layer 30 of the first embodiment.

Next, although not shown, a photoresist mask having an opening aroundthe track width defining portion 30A of the top pole layer 30 is formed.Next, as in the first embodiment, a portion of the fourth layer 10 f isetched by ion beam etching, for example, using the photoresist mask andthe track width defining portion 30A as masks. A trim structure isthereby formed, wherein a portion of the fourth layer 10 f, the writegap layer 26, the magnetic layer 53 a, and the track width definingportion 30A have the same widths in the air bearing surface.

Next, sidewalls of the portion of the fourth layer 10 f, the write gaplayer 26, the magnetic layer 53 a and the track width defining portion30A are etched by ion beam etching, for example, to reduce the widths ofthese layers in the air bearing surface down to 0.1 μm, for example.This etching may be performed such that the direction in which ion beamsmove forms an angle in a range of 40 to 75 degrees inclusive withrespect to the direction orthogonal to the top surface of the firstlayer 10 a.

FIG. 27A and FIG. 27B illustrate the following step. In the step theovercoat layer 38 made of alumina, for example, and having a thicknessof 20 to 30 μm is formed so as to cover the entire top surface of thelayered structure. The surface of the overcoat layer 38 is flattened,and electrode pads (not shown) are formed thereon. Finally, the sliderincluding the foregoing layers is lapped to form the air bearing surface42. The thin-film magnetic head including the read and write heads isthus completed.

According to the embodiment, the throat height is defined by theposition in which the end portion 26 a for defining the throat height inthe write gap layer 26 is in contact with the magnetic layer 53 a of thetop pole layer 30. That is, the throat height TH is the distance betweenthe air bearing surface 42 and the position in which the end portion 26a is in contact with the magnetic layer 53 a. The zero throat heightlevel TH0 is the level in which the end portion 26 a is in contact withthe magnetic layer 53 a. According to the embodiment, the top surface ofthe write gap layer 26 is not polished, so that there is no variation inthroat height caused by polishing even if the surface of the end portion26 a is tilted with respect to the direction orthogonal to the topsurface of the first layer 10 a. The throat height is thereforecontrolled with accuracy, according to the embodiment.

According to the embodiment, the nonmagnetic layer 54 is formed bylift-off to fill the etched portion of the magnetic layer 50. As aresult, it is possible to flatten the top surfaces of the magnetic layer53 a and the nonmagnetic layer 54 by a small amount of polishing. It isthereby possible to control the thickness of the pole portion of the toppole layer 30 with accuracy. As a result, the writing characteristics ofthe thin-film magnetic head are easily controlled with accuracy. If thenonmagnetic layer 54 is formed such that the top surface thereof islocated in nearly the same level as the top surface of the magneticlayer 53 ap, the step of flattening the top surfaces of the magneticlayer 53 ap and the nonmagnetic layer 54 may be omitted.

The remainder of configuration, function and effects of the secondembodiment are similar to those of the first embodiment.

Third Embodiment

Reference is now made to FIG. 28A to FIG. 33A and FIG. 28B to FIG. 33Bto describe a method of manufacturing a thin-film magnetic head of athird embodiment of the invention. FIG. 28A to FIG. 33A are crosssections orthogonal to the air bearing surface and the top surface ofthe substrate. FIG. 28B to FIG. 33B are cross sections of the poleportions parallel to the air bearing surface.

The method of manufacturing the thin-film magnetic head of the thirdembodiment includes the steps up to the step of forming the insulatinglayer 22 as shown in FIG. 7A and FIG. 7B that are the same as those ofthe first embodiment.

FIG. 28A and FIG. 28B illustrate the following step. In the step amagnetic layer made of a magnetic material and having a thickness of 0.3to 0.5 μm is formed by sputtering, for example, to cover the entire topsurface of the layered structure. The magnetic layer may be made of ahigh saturation flux density material such as CoFeN, FeAlN, FeN, FeCo orFeZrN. In the embodiment the magnetic layer is made of CoFeN having asaturation flux density of 2.4 T by way of example.

Next, an etching mask 61 a is formed in a portion corresponding to thethird layer 10 d and an etching mask 61 b is formed in a portioncorresponding to the coupling layer 10 e. Each of the etching masks 61 aand 61 b has an undercut so that the bottom surface is smaller than thetop surface in order to facilitate lift-off that will be performedlater. Such etching masks 61 a and 61 b may be formed by patterning aresist layer made up of two stacked organic films, for example.

Next, the magnetic layer is selectively etched by ion beam etching, forexample, through the use of the etching masks 61 a and 61 b. The fourthlayer 10 f and the coupling layer 10 g are thereby made up of portionsof the magnetic layer remaining under the etching masks 61 a and 61 bafter the etching, and disposed on the third layer 10 d and the couplinglayer 10 e, respectively. In the third embodiment the top surface of thefourth layer 10 f is the first surface 10A, and the top surface of aportion of the third layer 10 d, the portion being located farther fromthe air bearing surface 42 than the fourth layer 10 f, is the secondsurface 10B.

Next, an insulating layer 62 made of alumina, for example, and having athickness of 0.4 to 0.6 μm is formed to cover the entire top surface ofthe layered structure while the etching masks 61 a and 61 b are leftunremoved. The insulating layer 62 is formed in a self-aligned mannersuch that the etched portion of the magnetic layer to be the fourthlayer 10 f is filled with the insulating layer 62.

FIG. 29A and FIG. 29B illustrate the following step. In the step theetching masks 61 a and 61 b are lifted off, and the top surfaces of thefourth layer 10 f, the coupling layer 10 g and the insulating layer 62are then polished by CMP, for example, and flattened. The depth to whichthe polishing is performed is 10 to 50 nm, for example.

FIG. 30A and FIG. 30B illustrate the following step. In the step thewrite gap layer 26 having a thickness of 0.07 to 0.1 μm is formed tocover the entire top surface of the layered structure. The write gaplayer 26 may be made of an insulating material such as alumina or anonmagnetic metal such as Ru, NiCu, Ta, W or NiB. Next, a portion of thewrite gap layer 26 corresponding to the coupling layer 10 g isselectively etched.

Next, a magnetic layer made of a magnetic material and having athickness of 0.1 to 0.3 μm is formed by sputtering, for example, tocover the entire top surface of the layered structure. The magneticlayer may be made of a high saturation flux density material such asCoFeN, FeAlN, FeN, FeCo or FeZrN. The magnetic layer preferably has ahigher saturation flux density. In the embodiment the magnetic layer ismade of CoFeN having a saturation flux density of 2.4 T by way ofexample.

Next, etching masks 63 a and 63 b are formed on the above-mentionedmagnetic layer. The etching mask 63 a is provided for forming an endportion for defining the throat height in the magnetic layer, and isdisposed above the fourth layer 10 f. The etching mask 63 b is disposedabove the coupling layer 10 g. Each of the etching masks 63 a and 63 bhas an undercut so that the bottom surface is smaller than the topsurface in order to facilitate lift-off that will be performed later.Such etching masks 63 a and 63 b may be formed by patterning a resistlayer made up of two stacked organic films, for example.

Next, the magnetic layer and the write gap layer 26 are selectivelyetched by ion beam etching, for example, using the etching masks 63 aand 63 b. A magnetic layer 64 ap and a coupling layer 64 b are made upof portions of the magnetic layer remaining under the masks 63 a and 63b after the etching.

The magnetic layer 64 ap is disposed adjacent to the write gap layer 26.The magnetic layer 64 ap will be patterned to be a throat heightdefining layer 64 a. At this time the magnetic layer 64 ap has a widthgreater than the write track width. The magnetic layer 64 ap has an endportion 64 al for defining the throat height. The coupling layer 64 b isdisposed on the coupling layer 10 g.

Next, a nonmagnetic layer 65 made of a nonmagnetic material is formed bylift-off. That is, the nonmagnetic layer 65 having a thickness of 0.2 to0.4 μm is formed to cover the entire top surface of the layeredstructure while the etching masks 63 a and 63 b are left unremoved. Thenonmagnetic layer 65 is formed in a self-aligned manner such that theetched portions of the magnetic layer and the write gap layer 26 arefilled with the nonmagnetic layer 65. The nonmagnetic layer 65 ispreferably formed such that the top surface thereof is located in nearlythe same level as the top surface of the magnetic layer 64 ap. Thenonmagnetic layer 65 may be made of an insulating material such asalumina.

FIG. 31A and FIG. 31B illustrate the following step. In the step theetching masks 63 a and 63 b are lifted off, and the top surfaces of themagnetic layer 64 ap, the coupling layer 64 b and the nonmagnetic layer65 are polished by CMP, for example, and flattened. The depth to whichthe polishing is performed is 10 to 50 nm, for example.

FIG. 32A and FIG. 32B illustrate the following step. In the step amagnetic layer made of a magnetic material and having a thickness of 0.1to 0.3 μm is formed by sputtering, for example, on the entire topsurface of the layered structure. The magnetic layer is made of a highsaturation flux density material such as CoFeN, FeAlN, FeN, FeCo orFeZrN.

Next, a yoke portion layer 64 d made of a magnetic material is formed byframe plating, for example, on the above-mentioned magnetic layer,wherein the magnetic layer is used as an electrode and a seed layer. Theyoke portion layer 64 d has a thickness of 3 to 4 μm, for example. Theyoke portion layer 64 d may be made of CoNiFe or FeCo having asaturation flux density of 2.3 T, for example. The yoke portion layer 64d is disposed to extend from a region corresponding to the magneticlayer 64 ap to a region corresponding to the coupling layer 64 b.

Next, the write gap layer 26, the magnetic layer 64 ap, and the magneticlayer below the yoke portion layer 64 d are selectively etched by ionbeam etching, for example, using the yoke portion layer 64 d as anetching mask. The magnetic layer below the yoke portion layer 64 d thusetched is a yoke portion layer 64 c. The plane geometry of the yokeportion layer 64 c is the same as that of the yoke portion layer 64 d.The magnetic layer 64 ap thus etched is a throat height defining layer64 a that corresponds to the first layer of the invention. After theabove-mentioned etching is performed, the yoke portion layer 64 d has athickness of 1 to 2 μm, for example. The top pole layer 30 is made up ofthe throat height defining layer 64 a, the coupling layer 64 b, and theyoke portion layers 64 c and 64 d. The top pole layer 30 of the thirdembodiment has a shape the same as the top pole layer 30 of the firstembodiment.

Next, although not shown, a photoresist mask having an opening aroundthe track width defining portion 30A of the top pole layer 30 is formed.Next, as in the first embodiment, a portion of the fourth layer 10 f isetched by ion beam etching, for example, using the photoresist mask andthe track width defining portion 30A as masks. A trim structure isthereby formed, wherein a portion of the fourth layer 10 f, the writegap layer 26, the throat height defining layer 64 a, and the track widthdefining portion 30A have the same widths in the air bearing surface.

Next, sidewalls of the portion of the fourth layer 10 f, the write gaplayer 26, the throat height defining layer 64 a and the track widthdefining portion 30A are etched by ion beam etching, for example, toreduce the widths of these layers in the air bearing surface down to 0.1μm, for example. This etching may be performed such that the directionin which ion beams move forms an angle in a range of 40 to 75 degreesinclusive with respect to the direction orthogonal to the top surface ofthe first layer 10 a.

FIG. 33A and FIG. 33B illustrate the following step. In the step theovercoat layer 38 made of alumina, for example, and having a thicknessof 20 to 30 μm is formed so as to cover the entire top surface of thelayered structure. The surface of the overcoat layer 38 is flattened,and electrode pads (not shown) are formed thereon. Finally, the sliderincluding the foregoing layers is lapped to form the air bearing surface42. The thin-film magnetic head including the read and write heads isthus completed.

According to the embodiment, the throat height is defined by the endportion 64 al of the throat height defining layer 64 a. That is, thethroat height TH is the distance between the end portion 64 al and theair bearing surface. The zero throat height level TH0 is the level inwhich the end portion 64 al is located.

According to the embodiment, an end of the first surface 10A opposite tothe air bearing surface 42 is located farther from the air bearingsurface 42 than the end portion 64 al of the throat height defininglayer 64 a. According to the embodiment, it is thereby possible toprevent saturation and leakage of flux halfway through the magnetic pathof the bottom pole layer 10. As a result, the overwrite property isimproved.

According to the embodiment, the nonmagnetic layer 62 is formed bylift-off to fill the etched portion of the magnetic layer to be thefourth layer 10 f. As a result, it is possible to flatten the topsurfaces of the fourth layer 10 f and the nonmagnetic layer 62 by asmall amount of polishing. It is thereby possible to control thethickness of the pole portion of the bottom pole layer 10 with accuracy.Similarly, according to the embodiment, the nonmagnetic layer 65 isformed by lift-off to fill the etched portions of the throat heightdefining layer 64 a and the write gap layer 26. As a result, it ispossible to flatten the top surfaces of the throat height defining layer64 a and the nonmagnetic layer 65 by a small amount of polishing. It isthereby possible to control the thickness of the throat height defininglayer 64 a with accuracy. According to the embodiment, these featuresmake it possible to control the thickness of each of the bottom polelayer 10 and the top pole layer 30 exposed from the air bearing surface42 with accuracy. As a result, the writing characteristics of thethin-film magnetic head are easily controlled with accuracy. If thenonmagnetic layer 62 is formed such that the top surface thereof islocated in nearly the same level as the top surface of the fourth layer10 f, the step of flattening the top surfaces of the fourth layer 10 fand the nonmagnetic layer 62 by polishing may be omitted. Similarly, ifthe nonmagnetic layer 65 is formed such that the top surface thereof islocated in nearly the same level as the top surface of the throat heightdefining layer 64 a, the step of flattening the top surfaces of themagnetic layer 64 ap and the nonmagnetic layer 65 by polishing may beomitted.

The remainder of configuration, function and effects of the thirdembodiment are similar to those of the first embodiment.

The present invention is not limited to the foregoing embodiments butmay be practiced in still other ways. For example, although the throatheight is defined by the stepped portion formed in the surface of thetop pole layer 30 closer to the write gap layer 26 in the embodiments,the throat height may be defined by a stepped portion formed in thesurface of the bottom pole layer 10 closer to the write gap layer 26.

According to the embodiment, the thin-film coil incorporating the coils13 and 19 and the connecting layer 21 is provided. However, thethin-film coil of the invention is not limited to this coil but may be atypical thin-film coil made up of a flat whorl-shaped coil having onelayer or more.

The invention is also applicable to a thin-film magnetic head dedicatedto writing that has an induction-type electromagnetic transducer only,or a thin-film magnetic head that performs writing and reading with aninduction-type electromagnetic transducer.

Obviously many modifications and variations of the present invention arepossible in the light of the above teachings. It is therefore to beunderstood that within the scope of the appended claims the inventionmay be practiced otherwise than as specifically described.

1. A thin-film magnetic head comprising: a medium facing surface thatfaces toward a recording medium; a first pole layer and a second polelayer that are magnetically coupled to each other and include magneticpole portions opposed to each other and located in regions of the polelayers on a side of the medium facing surface; a gap layer providedbetween the pole portion of the first pole layer and the pole portion ofthe second pole layer; and a thin-film coil, at least part of the coilbeing disposed between the first and second pole layers and insulatedfrom the first and second pole layers, wherein: the first pole layer hasa surface facing toward the gap layer, the surface incorporating a firstsurface including an end portion located in the medium facing surfaceand an end portion located opposite to the medium facing surface, and asecond surface located away from the medium facing surface, the firstsurface being adjacent to the gap layer, a difference in level beingcreated between the first surface and the second surface, so that thesecond surface is located farther from the second pole layer than thefirst surface; the second pole layer incorporates: a first layerdisposed adjacent to the gap layer and including an end portion locatedin the medium facing surface and an end portion located opposite to themedium facing surface; and a second layer disposed on a side of thefirst layer opposite to the gap layer and including a track widthdefining portion for defining a track width; each of the first layer andthe second layer has a width taken in the medium facing surface that isequal to the track width; and a length of the second layer is greaterthan a length of the first layer, each of the lengths being taken in adirection orthogonal to the medium facing surface.
 2. The thin-filmmagnetic head according to claim 1, wherein the first pole layerincludes a portion adjacent to the gap layer, the portion having a widthtaken in the medium facing surface that is equal to the track width. 3.The thin-film magnetic head according to claim 1, wherein the secondlayer is a flat layer.
 4. The thin-film magnetic head according to claim1, further comprising an intermediate layer disposed between the firstlayer and the second layer, wherein: the intermediate layer has a widthtaken in the medium facing surface that is equal to the track width; anda length of the intermediate layer taken in the direction orthogonal tothe medium facing surface is greater than the length of the first layerand smaller than the length of the second layer.
 5. The thin-filmmagnetic head according to claim 4, wherein the throat height is definedby the end portion of the first layer opposite to the medium facingsurface.
 6. The thin-film magnetic head according to claim 1, whereinthe throat height is defined by a position in which the first layer isin contact with an end portion of the gap layer opposite to the mediumfacing surface.
 7. The thin-film magnetic head according to claim 1,wherein: the throat height is defined by the end portion of the firstlayer opposite to the medium facing surface; and the end portion of thefirst surface of the first pole layer opposite to the medium facingsurface is located farther from the medium facing surface than the endportion of the first layer opposite to the medium facing surface.
 8. Amethod of manufacturing a thin-film magnetic head comprising: a mediumfacing surface that faces toward a recording medium; a first pole layerand a second pole layer that are magnetically coupled to each other andinclude magnetic pole portions opposed to each other and located inregions of the pole layers on a side of the medium facing surface; a gaplayer provided between the pole portion of the first pole layer and thepole portion of the second pole layer; and a thin-film coil, at leastpart of the coil being disposed between the first and second pole layersand insulated from the first and second pole layers-, wherein: the firstpole layer has a surface facing toward the gap layer, the surfaceincorporating a first surface including an end portion located in themedium facing surface and an end portion located opposite to the mediumfacing surface, and a second surface located away from the medium facingsurface, the first surface being adjacent to the gap layer, a differencein level being created between the first surface and the second surface,so that the second surface is located farther from the second pole layerthan the first surface; the second pole layer incorporates: a firstlayer disposed adjacent to the gap layer and including an end portionlocated in the medium facing surface and an end portion located oppositeto the medium facing surface; and a second layer disposed on a side ofthe first layer opposite to the gap layer and including a track widthdefining portion for defining a track width; each of the first layer andthe second layer has a width taken in the medium facing surface that isequal to the track width; and a length of the second layer is greaterthan a length of the first layer, each of the lengths being taken in adirection orthogonal to the medium facing surface, the method comprisingthe steps of: forming the first pole layer; forming the thin-film coilon the first pole layer; forming the gap layer on the pole portion ofthe first pole layer; and forming the second pole layer on the gaplayer, the step of forming the second pole layer including the steps of:forming a magnetic layer for forming the first layer on the gap layer;forming the second layer on the magnetic layer; and etching the magneticlayer to align with a width of the track width defining portion, so thatthe magnetic layer is formed into the first layer and that the width ofeach of the first layer and the second layer taken in the medium facingsurface is made equal to the track width.
 9. The method according toclaim 8, wherein the step of etching the magnetic layer further includesetching of the gap layer and a portion of the first pole layer to alignwith the width of the track width defining portion.
 10. The methodaccording to claim 8, wherein the second layer is made to be a flatlayer.
 11. The method according to claim 8, wherein: the gap layer ismade of a nonmagnetic inorganic material; and the first layer is etchedby reactive ion etching in the step of etching the first layer.
 12. Themethod according to claim 11, wherein the nonmagnetic inorganic materialis one of the group consisting of alumina, silicon carbide and aluminumnitride.
 13. The method according to claim 8, wherein: the second polelayer further comprises an intermediate layer disposed between the firstlayer and the second layer, the intermediate layer having a width takenin the medium facing surface that is equal to the track width, theintermediate layer having a length taken in the direction orthogonal tothe medium facing surface that is greater than the length of the firstlayer and smaller than the length of the second layer, the step offorming the second pole layer including the steps of: forming a firstmagnetic layer for forming the first layer on the gap layer; forming afirst mask on the first magnetic layer for forming an end portion of thefirst magnetic layer opposite to the medium facing surface; forming theend portion of the first magnetic layer and forming the first surfaceand the second surface of the first pole layer by selectively etchingthe first magnetic layer, the gap layer and the first pole layer throughthe use of the first mask; forming a first nonmagnetic layer so as tofill etched portions of the first magnetic layer, the gap layer and thefirst pole layer while the first mask is left unremoved; removing thefirst mask after the first nonmagnetic layer is formed; forming a secondmagnetic layer for forming the intermediate layer on the first magneticlayer and the first nonmagnetic layer after the first mask is removed;forming a second mask on the second magnetic layer for forming an endportion of the second magnetic layer opposite to the medium facingsurface; forming the end portion of the second magnetic layer byselectively etching the second magnetic layer through the use of thesecond mask; forming a second nonmagnetic layer so as to fill an etchedportion of the second magnetic layer while the second mask is leftunremoved; removing the second mask after the second nonmagnetic layeris formed; forming the second layer on the second magnetic layer and thesecond nonmagnetic layer after the second mask is removed; and etchingthe second magnetic layer and the first magnetic layer to align with thewidth of the track width defining portion, so that the first magneticlayer is formed into the first layer, the second magnetic layer isformed into the intermediate layer, and the width of each of the firstlayer, the intermediate layer and the second layer that is taken in themedium facing surface is made equal to the track width.
 14. The methodaccording to claim 13, wherein the throat height is defined by the endportion of the first layer opposite to the medium facing surface. 15.The method according to claim 13, wherein the step of forming the secondpole layer further includes the step of flattening top surfaces of thefirst magnetic layer and the first nonmagnetic layer by polishing, thestep of flattening being provided between the step of removing the firstmask and the step of forming the second magnetic layer.
 16. The methodaccording to claim 15, wherein a depth to which the polishing isperformed in the step of flattening the top surfaces of the firstmagnetic layer and the first nonmagnetic layer falls within a range of10 to 50 nm inclusive.
 17. The method according to claim 13, wherein thestep of forming the second pole layer further includes the step offlattening top surfaces of the second magnetic layer and the secondnonmagnetic layer by polishing, the step of flattening being providedbetween the step of removing the second mask and the step of forming thesecond layer.
 18. The method according to claim 17, wherein a depth towhich the polishing is performed in the step of flattening the topsurfaces of the second magnetic layer and the second nonmagnetic layerfalls within a range of 10 to 50 nm inclusive.
 19. The method accordingto claim 8, wherein: the step of forming the first pole layer includesthe steps of: forming a first mask for forming the first surface and thesecond surface of the first pole layer on the gap layer; forming thefirst surface and the second surface by selectively etching the gaplayer and a portion of the first pole layer through the use of the firstmask; forming a first nonmagnetic layer so as to fill etched portions ofthe gap layer and the first pole layer while the first mask is leftunremoved; and removing the first mask after the first nonmagnetic layeris formed; and the step of forming the second pole layer includes thesteps of: forming a magnetic layer for forming the first layer on thegap layer and the first nonmagnetic layer after the first mask isremoved; forming a second mask on the magnetic layer for forming an endportion of the magnetic layer opposite to the medium facing surface;forming the end portion of the magnetic layer by selectively etching themagnetic layer through the use of the second mask; forming a secondnonmagnetic layer so as to fill an etched portion of the magnetic layerwhile the second mask is left unremoved; removing the second mask afterthe second nonmagnetic layer is formed; forming the second layer on themagnetic layer and the second nonmagnetic layer after the second mask isremoved; and etching the magnetic layer to align with the width of thetrack width defining portion, so that the magnetic layer is formed intothe first layer and that the width of each of the first layer and thesecond layer that is taken in the medium facing surface is made equal tothe track width.
 20. The method according to claim 19, wherein: an endportion of the gap layer opposite to the medium facing surface is formedby the etching of the gap layer; and the throat height is defined by aposition in which the end portion of the gap layer is in contact withthe first magnetic layer.
 21. The method according to claim 19, whereinthe step of forming the second pole layer further includes the step offlattening a top surface of the magnetic layer by polishing before thesecond mask is formed on the magnetic layer.
 22. The method according toclaim 21, wherein a depth to which the polishing is performed in thestep of flattening the top surface of the magnetic layer falls within arange of 10 to 50 nm inclusive.
 23. The method according to claim 19,wherein the step of forming the second pole layer further includes thestep of flattening top surfaces of the magnetic layer and the secondnonmagnetic layer by polishing, the step of flattening being providedbetween the step of removing the second mask and the step of forming thesecond layer.
 24. The method according to claim 23, wherein a depth towhich the polishing is performed in the step of flattening the topsurfaces of the magnetic layer and the second nonmagnetic layer fallswithin a range of 10 to 50 nm inclusive.
 25. The method according toclaim 8, wherein: the step of forming the first pole layer includes thesteps of: forming a first mask for forming the first surface and thesecond surface of the first pole layer on the first pole layer; formingthe first surface and the second surface by selectively etching aportion of the first pole layer through the use of the first mask;forming a first nonmagnetic layer so as to fill an etched portion of thefirst pole layer while the first mask is left unremoved; and removingthe first mask after the first nonmagnetic layer is formed; and the stepof forming the second pole layer includes the steps of: forming amagnetic layer for forming the first layer on the gap layer; forming asecond mask on the magnetic layer for forming an end portion of themagnetic layer opposite to the medium facing surface; forming the endportion of the magnetic layer by selectively etching the magnetic layerthrough the use of the second mask; forming a second nonmagnetic layerso as to fill an etched portion of the magnetic layer while the secondmask is left unremoved; removing the second mask after the secondnonmagnetic layer is formed; forming the second layer on the magneticlayer and the second nonmagnetic layer after the second mask is removed;and etching the magnetic layer to align with the width of the trackwidth defining portion, so that the magnetic layer is formed into thefirst layer and that the width of each of the first layer and the secondlayer that is taken in the medium facing surface is made equal to thetrack width.
 26. The method according to claim 25, wherein: the throatheight is defined by the end portion of the first layer opposite to themedium facing surface; and the end portion of the first surface of thefirst pole layer opposite to the medium facing surface is locatedfarther from the medium facing surface than the end portion of the firstlayer opposite to the medium facing surface.
 27. The method according toclaim 25, wherein the step of forming the first pole layer furtherincludes the step of flattening top surfaces of the first pole layer andthe first nonmagnetic layer by polishing after the first mask isremoved.
 28. The method according to claim 27, wherein a depth to whichthe polishing is performed in the step of flattening the top surfaces ofthe first pole layer and the first nonmagnetic layer falls within arange of 10 to 50 nm inclusive.
 29. The method according to claim 25,wherein the step of forming the second pole layer further includes thestep of flattening top surfaces of the magnetic layer and the secondnonmagnetic layer by polishing, the step of flattening being providedbetween the step of removing the second mask and the step of forming thesecond layer.
 30. The method according to claim 29, wherein a depth towhich the polishing is performed in the step of flattening the topsurfaces of the magnetic layer and the second nonmagnetic layer fallswithin a range of 10 to 50 nm inclusive.